It's a slow day and a Friday, so I started thinking, what kind of crap do I have kicking around my home? Well, I have a Raspberry Pi 2 and a cellphone power bank to run it from, enough old cell phones to be considered a hoarder, an RC car that could operate as a platform

My proposal: Old cell phone provides LTE data service to the Rasp Pi via good old 802.11, battery bank provides power to the Raspberry Pi and phone. Rasp Pi hosts a VPN server with a preconfigured IP Sec tunnel back to my home router providing remote access. Rasp Pi drives the RC car.

Challenges:
- IP addresses change: While the address on my home router does not change often enough to be meaningful, it is my experience that the cell phone address changes daily. The first thing the Rasp Pi should do is Email it's external address to aid in trouble shooting. The shared secret won't change between devices.

- Data Service: $20 a month through Mint Mobile gives me 10 GB a month on a 4G pipe so this should be sufficient.

- Getting the Rasp Pi to talk to the car: Neither device was designed to do any of this. I might punk out and go with this guys off the shelf solution: https://www.instructables.com/Raspberry-Pi-Remote-Controlled-Car-1/

- I will have to buy a Pi camera module. $50

Boom. Red neck Mars rover. Thoughts?

ditch the data service ... get a pair of radios for a one time fee.
you would only want paid-for phone tower if you go out of LOS or around the curve of the earth (quite a ways away).

Interesting, what protocol would that use? VPN is a form of encryption so as I understand it the 44 Net is out, I also don't know how prevalent HAM radio is in my neighborhood. You can't do video over Bluetooth and I'd like to avoid shortwave since that's a whole other layer of complexity.

This is exactly the kind of feed back I wanted. Thank you.

it could be anything from 'as if over an old time serial port' (no protocol, you send what you send and it listens to what it gets) to UDP like packets. Some of them can handle low quality video on the cheap, the more expensive ones can handle higher bandwidths. Ill look ... I have not been in the RC biz in 10 years.

Looks like a lot of modern stuff is using 2.4 ghz techs that you can talk to a computer with directly. Look for something with spread spectrum and 2x the range you think you will need, that you can talk to with that idea over say UDP.
This looks like a much better link than when I started.
https://oscarliang.com/radio-transmitter/#radio-receivers

I'd go with a VHF/UHF radio, since those generally operate with line-of-sight– 2 meters or 70 cm are both common bands in amateur radio. 1.25 meters is less commonly used, but that might be better for what you're trying to do.

Look into getting a ham license– a Technician class (the lowest one) will allow you to use the 2 meter, 1.25 meter, and 70 cm bands.

http://www.arrl.org/what-is-ham-radio

That should explain ham radio a bit. Get a manual– Amazon sells them for about $30 US.

https://www.amazon.com/ARRL-Radio-License-Manual-Spiral/dp/1625950829/ref=sr_1_1?keywords=arrl+manual&qid=1638468554&sr=8-1

A website that I used for studying for the exam was https://hamstudy.org.

Hope this helps!