Always bought new RV's and removed the RV mattress the 1st week of ownership. Replaced with an air mattress (usually AeroBed) with an internal air pump with a tethered inflation control for the divided each side. Layed an thick egg crate foam over it years ago but now put a 2" thick Memory Foam on top of the air mattress. Ends up the same total thickness as the original RV mattress so there's no clearance issues over our heads for hitting and the inflation can be controlled for both her and my likings. Works super.
The sliding door are easily removable and stored at home so the 1.5" additional length can be permanent and both sides will have open ventilation etc. If desired, an accordion type folding door can be mounted on the RV wall each side so it closes to the entertainment center if wanted or any distance desired on either side.
Sounds like you have a short queen bed (75" long) and maybe with a little work, the entire entertainment center can simply be moved 5" away from the foot end of the bed and screwed in place. Then a filler put in and an 80" long mattress used. That would give you 5" extra over your 75" (6'3") body length.
Any of this is so much cheaper than replacing a newly purchased RV. Think your way thru fixing your problem as that's free and can be very productive.
Food for thought!
edited to fix a typo