And, you can sew a few channels with different arcs. Thread the one you want to try. Or, fitting different stiff "rings" with different arcs through the channel, you could also easily change the effective lengths of the different parts of the bed.
Or you could sew several alternative channels to the end or ends of your hammock, using a separate piece of cloth for each.
A Clark in plain view has just one straight channel of different fabric, 1 1/2" wide, sewn to each end. Why not another channel, with a pronounced arc, right on top of the the one that's there? (4" with doubling x 50"wide = 200sq in . Divide by (36 x 36) and multiply by 60grams (wt sq yd) * 2 ends to see a weight penalty of just 20 extra grams for the alternative channel.