Thompson's works fine. Put it in a pump sprayer and have at it. Wear a respirator or at least a face mask....the stuff is very volatile.

I'm curious how yours stands up to wind and especially rain. With your ground cover extending beyond the tent footprint, you'll get puddles inside. Might consider 'bath tubbing' the cover to the inside of tent walls. The ones I made from tarps, caught the wind and had to be staked down really well. They were roomy, that's for sure.
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