I once spoke to him about 5X7, since that was the biggest enlarger I had when I first purchased his 8x10 camera; and and he suggested adapting a Cambo 5x7 back, which would in fact be fairly easy to do in any reasonably equipped shop like mine. But so was an 8x10 conversion to one of my enlargers. So I never took the 5x7 format route.

Incidentally, my early Phillips 8x10 is still functioning superbly after all these years of hard outdoor use. The penetrating epoxy which seals the originally blonde custom plywood has yellowed a lot; but that's not an issue as long as the camera is kept out of sunlight when not in actual use. Those kinds of epoxy sealants do crack and fail within a few years under constant daily sunlight, like on a front door or boat deck for example, unless painted over. It's a category of coating I have decades worth of experience with.