Dude you go a long way! I read the Hitchhiker's in '84 (I was only in teens then). So it did ring a bell. (BTW thanks for the compliment)
Anyways, have you tried modifying frodoplayer.ini and used the 800x480 skin in 800x600 mode? In fact I just realised that if you change the USE_ADVANCED_SCREEN_SETTINGS=true to false then FP goes fullscreen. Everything works normally, ie. I don't have to do any pixelmapping, which is great! Now I can go and do Brushed Alum skin for daytime viewing.