WE did the same thing for a lot of years,too. Carpet underlay foam with the vapor barrier on the underside is the greatest thing ever made for sleeping outdoors.
instead of a pool cover just use a tarp? thats what we usually do.
Afternoon Mangat I would be looking at a 16x24 walltent with five foot walls.You can fit 8 guys with cots and a wood stove.with a bit of room to move around.If you add a ten foot porch on the front it really frees up space in the tent as you can cook and store coolers etc... out side in the porch.I do have a couple of tents that size for sale.