I have a storm with a Canyon 55 and a custom dry box from Artisan Welding in Flagstaff. Supporting the locals with Canyon and Artisan. The dry box is about the same size as the Canyon.
I have only used the frame set up on 2 San Juan trips. We usually self support R2 it, with bigger water.
I am usually packed for 2. On the Juan, we had a partner 2 burner stove, small propane, kitchen for 4 and some food in the dry box. food/beer in the cooler. We still ran 2 Aire landing pads. For such a small boat, we can carry a ton of stuff.
If I get on the Salt this year, I will most likely self support R2 again. So much more fun.