A Box beam style would be your best bet for a break down, as far as length.
Put wheels on one end. Make it so you can lean or tilt it left or right.
I don't have a Box beam, I have several strongbacks for specific long canoes, of the T-top style. Using a Box beam, requires the Mushroom style of forms. In my opinion, they waste a lot of plywood.
The T-top style stem forms are cut so the shearline of the canoe can run Below the strongback top. Thus requiring less Plywood for forms.
I can remove the legs easily and store the strongback.
My Favorite Strongback is one I purchased from a builder in Minnesota. It came complete with a set of Merlin forms. The Builder was also very Precise in it's construction !
The thing I like most was the slanted legs ! They were easy to take off, and because of the angle, they were Rock solid in use !
Draw back was, it was designed for a 15' 8" canoe. You can adjust the stem forms a little each way, not much shorter.
