well on the mattress, I'd buy a memory foam one. their the best,, and you can cut it fit. you find that rv mattresses are a different size the home ones.
example is buy a queen size 60 x 80 inch and trim it down.
my rv size was 54 x 75
lots of rv mattresses also lots have a corner missing so to speak.
Chevy 2008 1500 X-cab 5.3 373 posi 4x4 z-71
2003 jayco quest 190 4059 lbs.
2004 Northern light 8.5