Some of the things we did to our 19CB:
Front receiver hitch for bike rack or scooter rack. Also good for extra ice chest.
Ditched the useless dinette table. I made a mini-table/make-up table for the wife from one of the uprights and a large cutting board.
Get a cover for the range. I made one from, you guessed it, a cutting board! (Not much counter space...)
If it does not come with swivels for the seats, get some. When you get parked, the swivel seats really add seating space.
There is NO room for a trash can inside, except for a small one beside the commode. We use a pop-up type outside.
Added shelving inside the bed area cabinets.
Lots of other stuff too! We are getting better at it every time we go camping! My wife, the smartest person I know, keeps a pad/pen handy and writes down every idea we come across while out.