Some of the deleted footage explain plot points much better (to the point of "Oh, that's what that was about.") or are have alternate shots that are much better.
A good edit would be:
The end of the last episode of series 7 (to explain getting back to Red Dwarf)
Most if not all of series 8 edited into one looong film. (Which can make the cross episode gag of Kryton's homemade penis work.)
Most of the deleted footage (trimming some less funny moments, trimming the timing of the jokes (there are some pauses during banter))
The ORIGINAL ending to series 8 which is a lot better and ends with our cast of leads back in charge and alone on the Dwarf.
It would be a good way of improving the crap that is series 8 and actually having a satisfying ending to the series.
Some effects shots might have to be completed unfortunately.