We have a popup tent too. It was cheap in price, and is a pain to wrestle down into the bag, but it can be done!
We use a brown astroturf doormat that we place at the bottom of our stairs into the camper, and it is perfect to stand on when showering. We have a tiny tripod table that has a cordura fabric top, which we bring into the tent for shampoo, soap and razors. A camp chair is stationed just outside, with towels at the ready.
I anchor the tent to the corner of our camper with a carabiner I have inserted through the spring steel tent structure, which attaches to a one of the rear steps on the camper, with a strap to lengthen if we are on a slope. The benefit of anchoring the tent is that we shower and leave the tent set up to dry, and in the morning it's still there! Our last night in DV was so windy, I strapped a rock to one corner, but the carabiner up top is what keeps the tent secure no matter what.
Hot water is supplied by our Zodi Extreme, which I power off a two gallon accessory propane tank. I used to heat the tank on the stove of the Hawk, but felt uncomfortable with the risk of being burned. Outside on the Zodi tripod is better, especially run off a larger tank than a one pounder.
We just used this system on our winter DV trip and had excellent steamy showers, which earned me bonus points with my S.O.