Nick says—
Tent platforms are usually the worst place for a tent. Hard packed ground that drains poorly and increases rain splash when it hits the ground. I understand that some locales require camping in designated areas, which is one of the reasons why I live on the left coast, not the right coast. Remember good site selection is rule number one for staying warm, dry, and safe.
I do all my backpacking on the Right Coast and have been for almost 40 years and have never used a designated site—but then again I never backpack in the overly regulated Smokies.
And I disagree with good site selection being rule number one for staying warm, dry, and safe. Rule #1 is having a shelter which can handle all sites without condition. (Short of falling trees or lightning strikes or tornadoes).
If a tent gets you wet on a hard-packed surface (and many many established campsites are packed)—get a different tent with a better floor and canopy and fly configuration.
If you want to camp on an open bald in a high wind blizzard but your tent requires you bail off the peak and hit lower ground, well, get a better shelter which will allow you the freedom to set up exactly wherever you want.
If you get to a camp at 6pm under clear skies and set up and then by 3am a hellstorm hits, have a shelter that can handle such a storm so you won’t have to pack up on a nighthike and bail.
Plus, in the Southeast mountains of TN and Georgia and NC where I backpack we at times get rainstorm deluges whereby tons of water hit our tent and run down our tent flys. Guess what? This water runs off the fly and has to go somewhere no matter where you are camped. All this water hits the ground around the fly and slowly “sheets” and travels under your tent floor (hopefully not your tarp) and if the rain is hard enough this water forms a temporary pool under your floor—point is your floor must keep this water out no matter what. Ergo the advantage of a tent with a high denier and high hydrostatic head.
What works for me? 70 to 100 denier floor with a 7,000 to 10,000 hydrostatic head. Just some thoughts.