Making basic 4X5 for field & astrophotography use

i'm looking for advice and direction as I haven't set out to build a camera before. There are quite a few websites on the subject, but not all of them are for first time builders.
The project started with the purchase of a used Polaroid Land 110A lens, a Rodenstock Ysarex 127mm f4.7 lens. For astrophotography I wanted as fast a lens as I could get on a minimum budget. Today I ordered a flange mount for it. The lens board will likely be wood with an aluminium plate on the lens side, as I'd like to mount some power resistors to it that will be used to slightly warm the lens itself to keep dew off at night.
Other than that, I'd like some ability to focus it.
It should be as light weight as practical, it will be used on a home made tracking mount (no star trails on longer time exposures).
The rear standard and film holder mount should be uncomplicated, not difficult to use in the dark.
I was thinking of looking for a parts camera and trying to transplant over parts to my home made shell, is this practical?
And I was thinking of making my own bellows.
fAs for a focusing screen, again i thought I'd use the screen from a parts camera or other source, or make my own.
This would be my first, and only, 4X5 camera, it would be nice if it could double up for some field use, it wouldn't need much if any movement, I don't think the lens I have would accommodate that anyway.
And perhaps the camera could also be used in an enlarger as I've seen done on at least one website.

Sorry to be a wet blanket but have you considered that composing and focusing the dark sky on ground glass may be impossible. It might be a good idea to invest some time on-line at astrophotography websites to see whether others are using large format cameras, and if so how.

You can get around trying to focus on the stars at night by setting the camera to infinity during the day and locking it down. I've focussed on stars before though. It is actually pretty easy as long as you have a bright one, and if you focus on one, you don't have to worry about depth of field! They will all be in focus.

For a camera, you might want an old Speed Graphic. You can strip off the rangefinder and even the shutter if you wanted. You could even strip off the leather if you really wanted to be thorough about it. What you would be left with is a lightweight camera. It is pretty simple to do it since you just have to take it apart. You don't need any movements either, so it would be perfect. And cheap.

If I were you I would use a Grafmatic for your holder. They actually pinch the film so it won't move during your exposure.

Hope that helps.

I wouldn't use a large format camera for astrophotography. They're heavy and most tracking devices will have problems moving them without shaking. Not only that, but you don't really gain much by using such large film. The stars are all just point sources. So you get essentially the same results on 4x5 film as you would using a 35mm with an equivalent lens. It's not like focusing on a distant mountain where you can gain more detail. You're still just recording one tiny spec, no matter what film size you use (unless you're filming planets, they're a different story. They're actually close enough that they're not point sources). That, and it's usually easier to find good 35mm lenses with the appropriate apertures and focal lengths than it is to find large format lenses. An f/4.5 is a fast lens for large format, but a rather slow lens for astrophotography.

I tried shooting astrophotography with my 4x5's before and found it frustrating and disappointing. Now, a 4x5 does do a good job with star trails, however. But when it comes to astrophotography, it's just really, really hard to beat a good DSLR.

Sounds like something I'd do(the camera). Rather than building a field camera, check out instructions for a 4X5 pinhole camera.They don't
use a traditional ground glass back but you could set a piece of GG in an extra film holder. It's probably going to be easier to make different
focal length lens tubes/extensions than one camera with a variable tube.
Something else to look at would be sliding box cameras, that might do for you. Then, if you liked just make a different sliding box for different length lenses.
The 127 is shortish normal on 4X5, think press camera.

Just looked at ebay & 45 pinhole cameras are way less expensive than parts view cameras.

Great feedback, thanks. I've had experience with large MF cameras, believe it not a Koni Omega Rapid, on the tracking mount and it worked OK. It is much heavier than a 4X5 I'd like to build. Also considered the focusing problem and came up with the same solution as Patrick Robert James suggested. Having some range of focus would be for some daytime use, it wouldn't replace a proper field camera. I had thought about using a metal bodied camera, but I learned from my MF attempts that the metal radiation cools too quickly and dew forms both on the lens and exposed metal. So I home made heated muffs for the lens, battery powered (needed the battery for the tracking table anyway) and it worked great. A wood and fabric (if I make bellows) design I hope will reduce the dew problem.
The challenge to home making I thought would be the rear standard / film holder mount.
For the Perseid shower a few weeks ago I did try to capture meteors using what I had on hand, fresh Fuji 200 colour film, and and Olympus OM-1 The results, well I'm not sure, on a roll of 24 frames each frame exposed for 6 minutes (likely overexposed seeing as the moon was rising and there was aurora coming and going) were not what I hoped for. I didn't have much luck even capturing satellite trails, but there were a couple of frames with something I hadn't seen before. I'd posted a couple of frames here https://goo.gl/photos/2pVW8Y8vtKDjnRE76 Unfortunately when I shared the photos with the Royal Astronomical Society of Canada "Ask and Astronomer" on their website he told me I'd photographed fire flies. Its a good thing he's an astronomer and not an entomologist, I don't believe that there are any fireflies within a couple of thousand miles of here.
Now as to why 4X5 for astrophotography, well I wanted to try it, I like large negatives. I'm not interested in the typical photos, and hardly interested in the common (up here anyway) aurora shots, I'd like to get a few good meteors, and the uncommon noctilucent clouds. Light pillars when its dark, created by ice crystals suspended in the very cold still air. Its and imagined thing, not real at all, but I get a feeling of these magnificent large scale optical delights don't fit on a small frame or digital sensor (to be manipulated digitally later).