You're gonna be swamped with suggestions. But, I bought a new 13' in 2010. And here's my suggestions:
Exterior 120v electrical
outlet. I added it but would order it the next time; extra 12v interior outlet.
I changed the cheesy reading lamps for Dome lamps...MUCH more warm ambient light
back there and still plenty of reading light
Screen door (Wife loves this); Sink in the bathroom...wouldnt be without this; an awning
and love it; Extra cabinets in the rear.
If you're getting the roof-mount A/C, I ordered the heat strip. Coleman also makes a digital thermostat for their units now that's VERY nice (I doubt Scamp
would install it..but they will the heat strip)
Ok...we've gone electric on the water heater. BUT, if you're going with propane
only, I would at LEAST go with DSI-- "Direct Spark Ignition". Otherwise you will be going outside to light
it and it can be difficult in wind. But just know that that is a "luxury". But I would still get it.
I would get the "Wizard" for the Progressive power converter (you'll have to check and see if they still use this brand) The "Wizard" will let you keep your Scamp
plugged in and never hurt the battery
but will keep it charged!
We got vinyl flooring over carpet. NEVER regretted it.
If you're not getting the "Deluxe" (wood model), then the standard model now comes with a 54" bed option. BUT, you lose galley cabinet space and lot of the closet so that's a call you have to make. But just know it's an option! Otherwise the bed is apx 44" wide at the shoulders and that can get pretty narrow!
I love the Fantastic fan, but I wish I had gotten the thermostat-controlled model. I would GREATLY consider that.
That's about it. But there'll be many other suggestions. But this is an opinionated start.