Interesting qs, as I was searching for a solution as most compediums are just too big for flat-bed view cameras (using Horseman VHR and FA) (also have lenses with 40.5mm filter thread - ie very small).
Found that the Flare buster by granview solves is the best solution. It is just a flexi 15" metal arm, with flash-leg (can changed to fit cameras tripod holes) at one end and on the other-end. a metal clip holding a black mat plastic shade. (I am sure this can be made cheaply DIY, although I did not bother as the above cost about USD20 only). For bigger lens, you might need a bigger shade. Also, the device is light, small and easy to carry around.
The solution might not be optimal for everyone, but do consider it.
Best regards.
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