Please go educate yourself.
FUCKING RADIOS, HOW DO THEY WORK?
How about you stop larping and go educate yourself?
CB.. 27 MHz
Fab all of the parts yourself so once they reconstruct it there's nothing to look up in factories as you made it. This also means creating from scratch the parts for the baloon and string etc etc. Just make sure to have it self destruct and to clean all fingerprints/human residue/residue from local area off all the parts and make it super clean.
=do it=
Your worst enemy would be getting triangulated.
They could measure the signal strength and do a massive operation to find you because why not and the police have too much free time.
Next would be implementing ECC and autoatically correct corrupted shit like how packets work and other shit that ensures TxRx quality from bad weather or interferrance because you're trying to go in the digital realm.
Get Ubuquity like this user says to save you time then have a unlocked router that has many features but don't let the Land of the Free know about your router.
Salvage parts. scrub off anything that can be used to identify shit after palcing them and make your own PCB or don't and have everything via wires, it's going to be a mess but if it works it works, and give it an isoprpyl alcohol bath before sending it out, just in case.
Nice suggestion user.