[Kidkraz]

I would look at adding a couple of USB ports. One in the front bed/couch area, and near/incorporated with the 12V cigarette plugs.
I'd go with a higher rating with the solar panels, or allow an extra panel to be installed during assembly. Maybe add an outside port so say a suitcase solar panel could be easily plugged in.

I'd delete the am/fm radio and pre-wired speakers. In hindsight, I would not have gone with the am/fm radio set up and speakers. One of my speakers is bad, from the start, but I didn't know that. I've used wireless speakers with my phone or tablet bluetooth. Make that area a small drawer for cables or a usb charging hub panel.

I'd like to see the folding bathroom walls more waterproof. Use a mold resistant or non-molding material or at a minimum seal the bottom where water tends to seep in an causes damage.

Beef up the oven wall nearest the door. As I get older, I'm finding that I'd love to add a grab handle or strap to grab as a hand hold to help when coming inside the camper. I've added one to the lower door half and already use the lift arm when entering.

Find a way to beef up the roofs to prevent sagging. Can a flat stiffener be on the inside or add something light weight but stiff to strengthen the shells.

Make replacing the kitchen sink faucets easier. Mount the faucet on a screw/bolted down stiffened plate. You could remove the plate, easily change the faucet and then reinstall the plate. Flexible hoses underneath only need to be long enough so you could get to the hose connectors. I had to remove my water heater to get mine changed. Nor should ya have to be Gumby to get to those connections.