I am looking to buy a prism viewfinder for my RZ, because in many situations i rise the tripod to a level where i need a ladder to look at that WLF, but i am trying to keep it at lower level so i can look at that finder from my position and no need to jump, but i would like to try if that 45/90 finders will help.
I also have Mamiya 7II, but still doesn't work, hope to send it one day for repair [i can't nowadays for reasons], and i chose this camera to be my outdoor/travel camera over RZ, but honestly speaking, all my shots of RZ are spot on, the focus with this RZ is amazing out of this world, opposite to my Hasselblad 501CM which i always not sure if the focus is there or dead or off.
About weight, i mostly use tripod outdoors for the things i shoot [landscapes, architectures,....etc], so i will not have that problem for using RZ, my Shen Hao 4x5 is lighter than my RZ by miles, so i shouldn't make the weight as an issue in cameras if i know how to use it and can do the job for me.