hi q-x

i hate to suggest this, because i know you specifically asked for advice for 35mm rangefinders with a m39 sort of situation ..
BUT if you can swing it, why not look for some sort of in expensive folding press sort of 4x5 camera? the lenses are just as inexpensive
in the FSU as they are everywhere else ... instead of 28,50, 135 you go 90, 150, 210 ... its easy as pie, AND
instead of film you can shoot cheap photo PAPER. easy to process ( even in instant coffee easy ) and make contact prints or those other thingys with a gizmo. ... if you find a speed graphic or similar, you can use ANYTHING for a lens seeing there is a shutter in the camera ... talk about cheap
the only set back is it is about 3x ( maybe more ! ) the size of a 35mm camera and then you need film/paper holders.

good luck with your conundrum !