Whoopies are spliced, no knots.
Knots weaken all cordage. Amsteel when properly spliced is practically like suspending a hammock with an equal diameter braided steel cable. You certainly don't sacrifice strength or safety using UCR or Whoopie Sling suspensions.
Concerning material or construction that will support 300+ pounds, that is easily done with either DL construction, and/or proper weight Sil or even a Tableclothfactory special, for that matter.
I would strap any of those to my back, with full confidence, long before I drag a 4 pound Roo into the brush. By keeping weight down on shelter and insulation, I can then actually consider, "luxury" or "comfort" items. Makes all the rest of the kit a lot lighter as well.
Don't waste your breath
Don't waste your heart
Don't blister your heels
Running in the dark