Bought a new enclosed trailer this summer and have recently been doing some upgrading. When I got it it was a basic 7x16 v-nose with an extra 8 inches of height. There was 1/4" plywood on the walls and 3/4" OSB on the floors. My long term plans for the trailer are to be able to haul cargo when I want, and to be able to use it as a mobile "hunting camp" in Dec/Jan when I hunt in Washington. Eventually it'll have an RV electrical hookup for 50 AMP power, an inverter, have outlets wired inside, and have an LED lighting on the interior. It is NOT ever going to be a "pull it into the field" trailer. I just finished phase 1 of it's transformation. The walls and ceiling are now fully done with 1" ridged insulation, there is 1/4" plywood across the ceiling, I laid a layer of 3/4" plywood over the floor bringing that thickness to 1 1/2", and I laid 3/4" plywood over the 1/4" on the sides. The new layers of plywood are laid opposite of what existed previously: if the first layer was north/south the second layer was east/west. Originally there were only 4 d-ring tie down points on the floor...one in each corner...and none on the walls. Now there are 14 d-rings on the floor and 26 on the walls. After cutting the new plywood sheets and installing them I figure I added 6-700 lbs of new weight which brings the trailer to around 3000 lbs. I'm going to flip the axles to under the springs and raise it about 3 inches total. I'm seriously considering swapping out the 3500# axles for either 5200 or 7000 lb axles. Future improvements will include a top vent, a window on each side, a removable bunk bed system across the back, scissor jacks under the back corners and a heavy duty load leveling anti-sway hitch. Eventually this is going to be an honest to goodness multi-purpose trailer.