There is also a growing movement in amateur radio to send text in a very robust coding scheme that can work in noisy environments.
She could have used a laptop and sent text messages via one of these protocols on VHF or UHF and use a code word book. This is what I would do. 220 MHz is very lightly used and 50 watts can cover the NOVA/DC area and avoid the repeaters. Even is the agencies intercepted the transmission, it could look innocuous, like a vegan recipe exchange.
She could have used a YAGI antenna and vertically polarized the signal, which would minimize the signal to a lurker.
It is not hard to build a tight communications security plan.
A friend of mine tells a story from rural Kansas. Some time back in the 1980’s. He was driving somewhere, out on a lonely road when he encounters this van with what looked like radio direction-finding equipment (antenna).
Just a regular-looking van - like they were looking for something.
Our guess is some sort of drug drop-off in the middle of nowhere and it’s picked up from some random point by someone knowing how to find it.
But that was just our guess all these many years.