“…use 4mil painters plastic for ground sheets…”

Another idea: cut your weight 82% and use 0.7mil sheet. It does collect moisture on the underside; but that’s manageable. And if you want real tough stuff for the low weight, use indoor window wrap (same as GG polycro ground cloth).

I avoid the lightweight thermal blankets for ground sheets as these seem to leave metal/silver/aluminum residue all over your stuff after 3 or 4 nights.