Don't know exactly how Bolers are set up, but my
Scamp has a fresh water tank under the curbside bench and the power center in the streetside bench. How will you access these components?
Agree with David. The benches are attached to a fiberglass lip on the wall and screwed to the floor. They add rigidity to the rear of the shell. If you look underneath you may be surprised at how little framing there is. If you take the benches out, the new bed structure should be bonded to the shell.
I'd be careful of how much
weight you add. RV cabinetry is not typically built of 2x4 stock. Go to an RV dealer and look inside the cabinets. You have to balance sturdiness against
weight. You could end up overloading the frame,
axle, and/or
tires.
I've been following another remodel in which the owner completely rebuilt all the cabinetry- very sturdy. The new cabinetry added about 400-500 pounds over the original fiberglass components, and the empty
weight now is the same as a fully loaded stock unit. (In this case the frame was rebuilt as well.)
Curious- what's your overall goal here? Why do you want to raise the bed? Storage is good, but the back of the trailer is not the best place. Too much weight behind the
axle can result in dangerous sway.