[oldE]

Because of the sideways forces exerted by hammocks and the desire for a stucture which could be easily set up, knocked down and transported, I would suggest expanding upon the basic design of the ubiquitous camp chair. Pivot points and triangulation along the sides with enough regidity to withstand the loads on the upper floor.

So, your basic structure is an expansion of the camp chair frame, the lower bedrooms would clip onto the framework for structure and privacy. The upper floor would be framed by fibreglass poles arched and captured in pockets at the corners and sides of the perimeter of the 'upper floor'. Then a lightweight shell would drape over the whole thing to provide weather protection.
Oh yes, anchor the sucker in case the wind picks up.

Les