I would never deploy a tent at a Walmart, or similar type place. Doubt the Manager would be too thrilled either.
I've sleep at Walmart many a night while on the road. I never unhook the TT. The most I will do is lift the tongue a little to level front to back, and on a rare occasion put a block under a wheel to also level the TT, should the TT be really out of whack.
I keep the slide in also. I'm at the Wally World only long enough to get a night's sleep. Then I'm up, possibly buy something at the Walmart before or after I sleep, and I'm then on my way.
I'd hate to lose this convenient way to get some shut eye.