Elkcrazy8 made two real good additions.

To reiterate:

(1) Any tent is a better tent under a tarp, this will allow you to consider the boxy "canvas condo family tent" if you have one that isn't too drafty, just make sure it will support weight of the tarp and the snow, unless you use the rope between two trees style ridgepole to carry the weight, still will be some indirect pressure on the tent. Main thing whenusing the Mr. Heater is you DON'T want snow on the same layer that your rising heat is going to "bounce" off of as that is just begging for a condensation problem.

(2) Cots are great for saving your floor space and for making things efficient (and easier to get up) but theyDO need a thermarest or something under them, your body gives off a lot of water thru the night and you don't want it condensing on the bottom side (top side is okay). Also make sure you put some padding between the cot legs and the tent floor to prevent damage, especially on unfavorable ground.