Both boxes I've had were/are accessible from the rear of the trailer. First one was all fiberglass and had door/hinge issues. Would be OK if the door would open 180 degrees without stressing the fiberglass. Second one is a slide out wooden box with a metal framework (homebuild).

I need the easy access to the box while the boat is loaded on the trailer, from the end, because I either forgot to put something in it, or want to get something out to fiddle with.