We started by pulling up the vinyl tile squares so we could put down a padded floor. We think we are going to go with those puzzle piece foam tiles you can get at lowes. I took down all of the luan board that was on the inside walls and put foam insulation sheets throughout the walls and ceiling. I then put up 3/8 plywood for a little more sturdiness.
We bought some E tracks for the walls to put up bunk beds like I saw somewhere on this site. We bought a fold out RV step which I will install tomorrow and a RV style door handle. We ordered some indoor outdoor carpet for the walls for a little more sound proofing. We have not decided if we are going to buy cabinets for the front end of the trailer or build some so we can customize them the way we like. I like the one that Don and Christi built on here. We are going to go with a portable room air conditioner to start with but may add roof top air later. This is what it looked like when we bought it, we are still scraping off the stickers.