Edit: But you said "mission screen over the usual F7 screen". Okay, I'm lost. I have no idea how to overlay a mission screen on an existing screen. I know how to intercept the F7 key press event, and would be able to display a mission screen instead of the F7 screen, but to integrate both... beyond me at this point. Do you have your sample still around that I can check out?
Okay, that's not what I meant. Are you going through a literal parsing phase? So you've identified two problems:
You'd have to leave off the rotating planet.
Any OXP's that integrate data on the F7 screen would need special attention.
The first wouldn't bother me at all, since it would provide an obvious visual cue which screen you were looking at. Use a background image with "First stop en route" in big letters where the model would normally appear. Confusion is likely to arise without some such indication.
The second would be the deal-breaker, since it would give it the home-made vibe. Explorers' Club provides a public function for just this situation, but what other OXPs would need to be considered, I dunno.
Other people would think it the other way around: wanting the planet model present to avoid an amateurish look, and accepting the replacement of the description text to indicate which screen they were viewing.
I'll mind my own business now; excuse the interruption, please, thank you.