We had the short queen in the 2000 Four Winds with no slides; my feet were always hanging off the end. The new Sunseeker has a full queen in the slide. My feet rarely hang off the end, except when I want them to. I'm 6' (and shrinking).
That's a good idea for a short queen.
The lower half of ours is snapped to the base, so it wouldn't move even if we wanted a bit more length. There's so little room between the end of the bed, my wife wouldn't be able to make it on her multi-trips to the bat-room at night.
Formerly: 2000 Four Winds 26Q/Ford, '96 Kit Sportsmaster 22' 5th wheel, '91 Sunlite truck camper, Wildernest flip-top canopy