Who knows why the control is on the door side, it makes no sense.
When I was inquiring about a new trailer I asked about having it relocated and was told no.
When I had my LevelUp installed I had the shop just leave the controller on the floor of the basement. There was enough wire to mount the pad just about anywhere I wanted. I chose up high next to the UDC.
There are only 4 wires on the the controller that would have to be extended if you didn't have enough wire already. The controller itself is about 1/2" thick.