I kind of see where you're going with that. Interesting idea. I guess a Prussik would spread out the constriction, particularly if one were to use extra wraps in the Prussik. I'd have to try it. Under field conditions, with the kind of strain that a human body would put on the knot as one wriggles into the hammock, I'd be afraind that the Prussik would constict primarily at a single point, possibly leading to a failure of the type I described earlier.

Alternatively, one could replace the ridgeline with something less sensitive to constriction.