alice, i looked into using a scamp
door but after getting prices from scamp i decided to build my own. the $150 (or so) wasn't so bad but the shipping to get it here was crazy. like $250 because it had to be shipped in a crate.
i started by making a foamcore (you could use large sheets of cardboard also) mock up to figure out clearances, etc. by taping the mock up to the fridge
wall at the entrance. the critical clearance issue was where the air conditioner sticks out from the wall. when i was satisfied that it was, in fact, possible i began building a frame with 1x2's. after a lot more adjustments to compensate for the thickness of the wood frame i had a working door. adding the screen and trimming out was the easy part. i don't have any drawings and they would be of little use since no 2 casitas are exactly the same. i hope the attached pictures are helpful.
if you decide to make a door you can find a full documentation on the casita
travel trailer forum by using the "search" function. also, if you have any specific questions don't hesitate to ask.