California camper prices are usually obscene so what's your idea of a "good price" on the 10 year old Roo 21ss. Driving to the Midwest or Ohio may not be an exciting option but is sure to save several thousand dollars. (I saved $4000 over "local dealer" prices just driving cross state.)
The "slightly smaller" bathroom on the starboard (curb) side of Roo/Shamrock campers is enough to make the door difficult to close when sitting on the potty. I consider that a liability.
These trailers were 90" wide and 76" ceiling height until circa 2006 thru 2008. I recall the ceiling height increased in 2006, a year or two before the body width. There are also "early" and "late" variations in the model year. My "early 2006" Roo 23SS has the 76" ceiling height for example.
Beds did not change with the body width. Same bed doors.
6" is really a massive change to the interior especially with the slide closed and in the case of the Roo 21SS and 23SS access to the rear bed.
I see a theoretical towing capacity of 6500 pounds if properly equipped which should handle either the new or used trailer.
Low water pressure in the shower is expected as there's a restriction in the head to limit water use. Torn awning is a sign of poor maintenance if it wasn't repaired -- what else wasn't repaired?
-- Chuck