Yeah, I'm not sure how much it would matter. Since it's a sort of ray tracing exercise to begin with, I might think front or back would potentially have the same problems. Maybe the inside mount would have less opportunity to gather additional dust in field use. I have a pinhole body cap adapter I made for my Bronica which has the flap shutter behind a circular plate and a sunshade (made from a black spray paint can lid!) that would allow me to easily put a filter adapter on the front. I considered it, but have never gotten around to it.
My later cameras have a pivoting flap shutter on the front and would more or less have to put the filter inside. Being that they are LF, with standard filmholders, that wouldn't be all that inconvenient. (No problem at all reaching inside the 8x10 version! )
Dang, now the wheels in my brain are spinning for rev. 2 for the next WPPD!