Light Weight Monorail
I'm (mostly) an Arca-Swiss man when it comes to LF. My lightest 4x5 camera is an Arca 'field' model: this is the older style one, old enough to have natty red bellows, not the current 'F-field'. With a back, 16" rail, GG, but no lens or film holder it weighs 4lb 10oz - of which a whole 1lb 1oz is the back and GG (this is using a screen with a fresnel, which adds a little weight, and the lightest type back, which saves some.)
I think that's pretty good for a monorail. This model doesn't have axis tilts and none of the movements are geared (I have those things on other cameras, and they all add weight) but it is very rigidly built, has interchangeable bellows, and a very wide range of movement.
Don't ask what my studio 4x5 weighs: I don't have scales that go that far...
Peter