Just a thought
Is it possible to use/make an IR-filter that fits in the darkslide on the filmback.
Ofcource it needs to be fitted in a way that prevent lightleaks.
Can it be made thin enough ? perhaps not
How about scratches and dust ? Could be a problem.
Is it a problem that it is so close to the filmplane ?
I have heard about fitting some kind of IR-filterfoil just behind the shutter in a 35mm SLR so I just thought.......