I've tried this with a few of my own (I create lots of planes using FSDS3.5). The biggest problem I've run into so far is that if my 2d panel takes up too much real estate (i.e. not much sky area at the top) then parts of the weapon hud etc. overlap my panel area. So I'm thinking of making some tweaked panels using FS Panel Studio (my editor of choice) where the main 2d panel gives more space to the HUD, and so forth. A couple of times the red and green circles in calibrate have been rather difficult to line up and adjust.