On the first fuselage I used the baggage shelf behind the seat for my camping pillow, foam pad and sleeping bag, all light weight stuff.
It also had a box built between the rear of the instrument panel to the rear of the firewall. It measures 9"x 12"x 23". Have a small door on the right side and I could get my light weight tent, extra clothes , etc. Also has a pouch on the rear of the seat back and on the floor behind the seat I have a small box for extra Qt of oil, paper towels, tools, etc. Still extra room under the seat and also the seat cushion has a zipper and you could put extra underware, etc, in the cushion. Lots of storage for such a small airplane.
Also the space for the forward baggage area could be used as another fuel tank area with room for 4=5 gal of extra fuel, but with over 16 gal in the wings and a fuel burn of 3 gph, I would rather use it for the baggage. 3-4 hrs between stops is OK for me.
Small baggage door in picture.
I need to build the forward baggage box before installing the plywood sides.