I haven't been carrying anything bigger than my little folding saw lately because others get to the bigger stuff pretty quickly and I am getting old enough to let them worry about the bigger stuff. That said I have used a home made buck saw in the past. It is a wooden frame that breaks down into 3 pieces and I used a bow saw blade in it. I typically carried it in a little 18 liter backpack with some pruning shears, work gloves, and what not. I like it better than the Sven saw which I found to be kind of flimsy. In the more distant past I have carried a chainsaw and stuff in a trailer.

On another note...
I have recently purchased a pole trimmer that has a lopper and a saw on the end of a long pole. Mine is from Fiskers. Anyway the blade is 14" long and even working with the long pole I managed to cut some branches as thick as 6" or so. That blade mounted on a much shorter handle might be pretty effective and easy to carry.

Also possibly consider a battery recipricating saw like a saw all. I saw 9" pruning blades that I'd think would work well for some of the stuff you would want to cut.