It's a tough market niche. Anyone with enough skills or gumption to assemble or adapt a generic flat pack kit won't have much tolerance for a big price markup. And shipping sturdy wood products is an expensive overhead cost. I don't think you'll find much of a market.
Considered doing the same thing myself, when I grasped how crazy expensive a lot of the stuff marketed to the 'overland' crowd is. Especialyl when I saw the astronomical pricing on chuckwagon boxes.
Still thinking about trying to do it on a more local basis. See the woodworking link in my sig.
I built some adirondack chairs and a convertible bench / 4-person picnic table, sold some, but shipping really drove the prices up and putting enough profit margin on them really drove their price well above what china-manf and plastic products cost for equivalents.
You might find a better market to create a kit design and sell the blueprints, with an option for customers to buy the kit. a la Ron Paulk's portable workbench plans. He's sold a lot at a low price, there's endless examples of his design on the net.
I sold a few of these, but the pricing was just too high. And shipping was nearly $100 due to the weight. And in redwood. The chicom versions were available for half as much. And ultimately I didn't want to spend a hot summer camped at the swap meet trying to generate some orders / sales. Maybe in some future better economy when people have more available money for luxuries.
