Alan
. Hmmmm
The Box stringers DO NOT run all the way to the transom
the picture below shows two battery shelves (that are nothing more than some plywood with glass over them
. (Read that as no stringer support) this shelf extends back to the transom.
On this boat (76 23 CC) you see in the picture that the stringers move outboard (to make room for that shelf)
As they near the transom however they cut the stringers height in half prior to reaching the transom. (ignore that black circle)
Starboard side looking aft
As Jason mentions above, the stringers wall, except for four or so feet in the stern of the boat, lay right on top of the transitions in the hull bottom
i.e. running strakes
.
The distance between the insides of those stringers is approximately 30
Personally if I had a bunk I would
THINK you would want to be as close to that area as possible so all that weight would transfer to the stiffest part of the hull (right into the stringer wall) OR would want keel rollers to bear a fair amount of the hulls weight.
If your not sure I would call a trailer place and ask them how to set it up
.even take it to them and let them set it the right way