Been there, using 3 diff.trailers. We ended up going back to an alum. 5x12 v-nose trailer to haul things.
I would suggest trying the idea out before you really get into putting time/money into it . We thought it was a great idea but didn't care for it after we tried it .
We just didn't like spending time inside when we could be outside.
After selling our 28 ft snomo trailer that we converted for a L.room , we downsized to another snowmobile trailer . I enclosed an 8x10 using alum 1x1 stock , 1/4" plywood covered with fiberglass mat. That is holding the roof snow better than the 28 ft'r , and is rock solid.
We used it as our snomo changing room as well as towed it when we camped in warm weather . It hauled our stuff and it was used as a spare bedroom and L.R. on occasion. (everything inside was all removable and portable, loveseat, flat screen, elec. fireplace)
We didn't use it . It was ok and got the job done but we really didn't like being inside. We needed to be out in nature.
It ended up being my DW's heated walk-in closet/changing room which we parked outside the CG bath house.
What we have done now , we did a simple truck camper dinette alteration to afford us more elbow room and a lounge chair set up. WE use our Cargo Pro trailer for hauling all our stuff.
Our trailer with our add a room is our extended kitchen now and extra cassette toilet to offset the dumping issue. We have found this set up to work better for us. The cooking/eating space proved to be the better more useful option. I can enclose my awning off my trailer and heat it as well.
Im in the process of making the awning larger 16x24 with full sidewall enclosures. It will be an outside kitchen/dinning room with enclosed access to the inside of the trailer . We do have a sat dish tv flat screen hookup out there that we have used for news/weather. This pic is the set up w/o the enclosure in place.
Here is a company that offers a set up, you can use it for ideas if you already a trailer to convert.
aluminum cargo/camping trailer