i made the best choice of my life when i started sleeping under tarps.
above the ground that is..
if flying bugs are not an issue, for the weight of a UL bivy you can get a Warbonnet Traveler.
for the weight of a Prolite short you can get a te-wa underquilt (13oz, in stuff sack, down to high twenties)
'round here there's plenty of scorpions, rattlers, gila monster, large spiders, ants, centipedes and so on.. im not going to be lunch!
visit the hammockforums and expand your horizons 10,000%
or, dont. ymmv.