Did you ever get a response to this question? I had to remove the panel to install a trailer harness recently. I ended up breaking one corner because apparently there are 4 screws holding it in place - that have to be accessed from inside the wall. Not sure how that works. I expected it would just clip in - but nope. I have yet to re-install it because I'm not too sure how I'm going to get my hand in behind to tighten 4 screws. The only reason I was able to get it out in the first place was that I broken one corner, leaving the screw behind. I managed to wedge my hand and a small screwdriver in behind the panel to get the other 3 screws out. I think the only way to re-install the panel is to remove the entire interior panel . . . which defeats the purpose of an "inspection" or "access" panel . . .
