I have been paddling the Old Town Canadienne ( the 15 footer) from the bow seat turned around. Even with my dog and a small cooler in the bow the boat is not trimmed very well. I like day paddling this boat, but will also use it for overnight trips. I am planning to add a more center seat and just have two thwarts, one behind the seat, and one toward the bow. This seems like the standard set up for quality solo boats. Then there is no center thwart for portaging the boat.
Any rule of thumb...