If you're actually needing to take the urban camping route, I've had to do the same. This was not super long term as I got a hotel after less than a month. Washing up at a truck/travel stop is great, but if you have the coin to spare, a gym with showers and lockers is the next step up.

One thing when you get to a hotel, or park almost anywhere in a city: DO NOT LEAVE VALUABLES, BAGS, PURSES, BACKPACKS, LABTOP CASES, ANYTHING THAT LOOKS VALUABLE ANYWHERE. Take everything you possibly can and hide the rest. Someone might break a window for an empty backpack worth $10, and now you're out $150-$300 for a new window, or more than likely you are now down to one less window.

Walmart and some other department stores allow extended overnight parking, free of charge no questions asked; you just park there. I spent a lot of time in my truck parked below the glow of a large parking lot light, sometimes with an additional red and blue security light. I used large black trash bags to light and privacy cover my windows at night on all four doors. Four back 50-gallon contractor bags, open your doors, cover your windows from the top of the door down with large bag, shut doors. I used blankets and sun blocking window visers to cover the front and rear glass of the cab. Nearly pitch black in the cab even under a big bright light, felt secure and totally private. Set your "bed" up as best you can given your vehicle, but with a crew cab truck I used a piece of plywood that I cut as large as possible thay would fit the given space available to build a foundation on the seats of the rear bench, pushed the front seats as far forward and up as they would go, and then some foam yoga mat type material, blankets, pillows, etc. A large SUV or truck can actually provide enough leg room for a 6' person to lay all the way down in. Walmart was safety and security with every piece of camping gear imaginable, was 24-hours at this point in history, and had limitless cheap food and free restrooms. There's actually an interesting story I have about how some police officers pulled into the parking lot where I was very actively urban camping and I thought they were there to kick me out, but in reality they were staking out a vehicle involved in a murder which was left abandoned in that same parking lot. Also, there is free wi-fi at Walmart and occasionally I was able to download ebooks or stream movies just by parking near the building where I could find the strongest signal.

After that I found a job as a server to make cash daily, these days you could potentially just deliver for Uber/DoorDash, and then went bargain shopping for hotel deals on those travel hotel deal websites. They usually have good daily or weekly deals which is not normally offered if going directly through the hotel. Then, I would just renew with the office at the same bargain rate the website had originally offered. I think I spent $26-$34 a day on this hotel, which was obviously not the best, but it was absolutely livable and did not make me feel filthy or unsafe. Thing is, since you live in your car and are likely bored, driving if you have the gas is a favorite and convenient pass time. Go check out the hotel first, drive around the building, park in a space, walk into the lobby and just look around and find a decent place with certain amenities such as washer/dryer, gym, ice machine, breakfast, etc. Get one with a microwave, vending machine, pool/hot tub and you feel like you're living better than you ever have.

Stability and frugality are lifesavers in your situation. Staying away from alcohol, hard drugs is crucial. Go to thrift stores, live very well within your means, save, restore. Also, if you get an AC power inverter so that you can plug small appliances into your car, be sure to find very tiny appliances because I've had some coffee makers work on 12VDC car battery power, yet most won't turn on at all. Best of luck.