: It shouldn't be that difficult at all, actually. You can build toothpick
: bridges that hold several hundred pounds of direct load.

True but it's apples and oranges. Those toothpick bridges use different method of construction. They are not framed with plywood ribs and long stringers. They have a lot more triangular members (typically). So it wouldn't be Yost style.

But it is possible to get them extremely light weight. Check out Plat Mumfords boats. They are about as light as they get. www.gaboats.com