That Bondo spot putty is great stuff, just have to be careful and use a flaat backed piece of sand paper or a file on it cuz it's so soft. It's meant to fill small paint chips in car doors.
It's a while since the last post as I've been putting off what may have put an end to the project; opening a perfect hole in the fuselage for the camera port and figuring out how to make the glass for it. I punched out a clear disc using something I picked up in the emergency room years ago(to anyone that keeps me waiting for almost 4 hours...I go shopping) and traced around it on the radio hatch. I then chain-drilled a series of holes inside the outline(breaking my 78 drill on the last hole), joined the holes together with a scalpel blade and then used a round file. Just need to run some fine sand paper around the hole and done. The next bit of pondering involves making the camera port fairing but at least I can join the fuselage halves together now.
Good stuff Geo. From what I remember when I converted a MkXIV and the old Monogram MkIX, I think I just drilled a pilot hole, then used a larger drill bit to drill a bigger hole, then filed that to size, using the punched-out transparency as a guide. But your method seems to have worked equally as well!