I use all of these items personally whenever I’m camping either in a tent or in my car.
1L or larger water bottle with a wide mouth cap ($2)
It’s annoying, cold, and potentially dangerous (particularly if car camping) getting up in the middle of the night to go. You can find these super cheap at thrift stores. If you’re female or can’t find a wide mouth bottle, add a pee funnel.
High capacity water jug ($15)
I find that one or two of the tall, 5-gallon ones are the easiest to carry while not taking up much space. Mine fit and stay in place well when placed on the floor of my rear passenger seats, wedged up against the front seats. They will leak if you don’t keep them upright. Reliance or Igloo seem to be the best and are about $15-20/each.
1-Gallon water jug with the wide cap ($1.50)
Poke holes in the lid and you’ve got a portable shower. A slightly more expensive, but versatile option is one of those portable dog shower nozzles that will fit on pretty much any 2L bottle.
You can also use this jug to refill your 5-gallon jug with tap water from anywhere so that you’re not conspicuously lugging a giant canister around.
Stove system ($15)
So you can boil water. For showering using the 1-gallon jug: keep the jug half filled with water and pour in boiling water - it will even out the temperature and you’ll be able to get very clean. Any Piezo igniter will do and they’re about $10. Use with an isobutane/propane canister - cheaper if you can find them locally at Walmart or REI ~$5.
It usually only takes me about 3/4 of the 1-gallon jug to shampoo/soap up and rinse, but it will depend on how much hair you have. Look up navy shower if you don’t already know how to use a small amount of water to get clean.
Hot water bladder ($15)
You can fill one with boiling hot water and it will add +15F to your sleep system easily. It’s like having another body next to you. I recommend getting one with the knit/fleece cover as it will prevent you from getting burned having it right up against your body.
Way cheaper, safer, and more discreet than keeping your car running or using one of those propane heaters in your tent. Do not throw Hot Hands into your sleeping bag, they will create moisture.
Campendium for free places to stay. Most states have a lot of free sites, especially out West.
In all, this system will cost you less than $50. More ideas (and my original comment) in this reddit thread.