Rob, I'm sure Scamp
would sell you an overhead fiberglass cabinet ... problem is, would they match the contour of your Boler
? You might have to cut and shape a little, depending on how it fit.
The cabinets are held up in place by pop rivets ... which would be pretty simple to add to any trailer.
Would also think you could build a wooden overhead cabinet ... making contoured wooden sides, floor and face plate, complete with hinged door ... but your carpenter skills would have to be a lot stronger than mine! Your wooden overhead cabinet could be held into place with some carefully placed little angle-irons, attached to the wooden frame, and pop riveted through the fiberglass trailer shell.
rear cabinet, for example, extends all the way across the back of the top of the trailer. You can store a lot of stuff, provided you can build it.
I'd probably go the wood route ... keep us posted on your progress!