If you camp in areas with privacy a Planet Fitness membership is not necessary. Buy a plastic wash basin typically used in kitchen sinks at any grocery store, less than $5 at Walmart. Boil a pot of water on camp stove add water until temperature is reached you find comfortable. Fill a 16 ounce red plastic tumbler and hold head over basin and dampen hair on scalp. This way you won't waste the water. Lather hair with shampoo and rinse off using the red plastic tumbler. Remember don't rinse hair over basin or water will get soapy. You don't even have to buy a whole sleeve of red cups, just find one in any ditch on the side of the road. It takes no more than 3 cups of water for rinsing, depending on how long and thick your hair. Next dampen your body and a wash cloth. Lather up wash cloth with your favorite body soap and lather up body using the wash cloth. Easier to wash your back if you have a wash cloth and it scrups your skin better as well. Then rinse soap off using red cup. Maybe takes 4 or 5 cups to wash and rinse body. So it takes 16 times 8 ounces or 128 ounces or one gallon of water to bath. Another method to heat up water is to buy a solar shower. They typically have at least a 2 gallon capacity. Those are great for heating water and pretty worthless for actually using as a shower. The stream is very poor unless you hang it very high and it's difficult to find a place to easily hang them from. Another tip wear sandals and stand on a rock or a hard surface so you don't get your feet muddy. Also if your area is not totally private, bath at night in the dark. I don't understand why anyone would want to stealth camp in a city. Being surrounded by the servile society is too depressing for me. I only occasionally city stealth camp. Better to find a spot outside the city and drive in for supplies periodically. Happy vanarchy everyone.