Mac, seems like you and me are having a conversation this morning.http://www.amazon.com/Slumberjack-Tough ... r-mr-title
Above is the link to the cots we used. I'm 270 lbs and this thing is built solid, rated to 350. I checked out the one you are looking at at a local Sportsman's Warehouse and was not impressed. As soon as my wife and I sat on and laid down on the Slumberjack we bought two, and this was after checking out at least five or six heavy duty cots. There was VERY little sway at all any time we were using the Slumberjacks. I reviewed it on Amazon too.
In the past we used little wooden 6"x6" blocks with rounded edges to protect the tent floor, but it was merely a cautionary move. For this year's burn I brought 6"x6" rubber pads cut from an old exercise mat. We ended up not using anything. The footpads on the Slumberjack were wide enough that they did not dig into the playa nor did they do any kind of damage to the floor of our Kelty 6 person tent. The floor of the Kelty is thin but tough. If the floor or your tent is tarplike, you might want to use something. You could easily use folded cardboard if you felt you needed padding.
We covered the cot with a 3" foam pad that cost $20 that perfectly fit the cot. We picked up the foam pads at hardware warehouse last Spring. Wow. Talk about decadent camping comfort. Slept like a log!
You are always smaller than anything that upsets you. Remain calm and solutions with boundless possibility will find your heart.