Currently have a very well built trailer and tub sitting on 35" tires. My sleeping quarters are a Autohome Columbus RTT. Just spent 66 days camping in Baja and really got tired of struggling with zippered doors and climbing the ladder. The box is 70" by 46" inside with 2" boxed top rails. Obviously this is too small for a livable camper but my plan is to extend the sides and front of the box about 6" with welded on "shelves". I'm only 5'10" so that would be adequate for sleeping room. Any other thoughts on how I might enlarge the box.The box sides are 15" high and I would like overall height to be full sitting up room but sides no more than 48".
Little more info on what I'm thinking. I'd like the front wall vertical so one could sit against that wall for reading, maybe 24-30", then tapered back for streamlining. The rear wall should be vertical to facilitate a full height door.
I'm wondering where you plan to add the 6" "shelves" to the existing trailer. Would they be at the top of the current box? The problem I'm seeing is this: if you put those shelves at the top of the current box, then all of the extra length you're looking for will be on top of the box. If you then build a camper top with enough headroom and put it on top of the current box, the finished trailer will be very tall, probably too tall.
If you extend the width at the bottom of the current box, you'll need to remove the current box or it would be inside a camper top, making the inside of the camper top very awkward to use.
The nice thing about a roof-top tent on this trailer as you've been using it is that it's low when the tent isn't deployed, and it doesn't matter how tall it is when the tent is deployed.
To do a camper top with a reasonable overall height and a practical inside headroom height, you generally need to mount the camper top right on the trailer frame. Your current box gets in the way of that, so I'm wondering what you want to do with the current box and these shelves you mentioned.