Given the terrain at JT I would absolutely get a GMRS radio with at least 5w of transmit power and has a removable antenna. Here are a few examples:
https://youtu.be/vzjs6uu5MJU?si=IeN2ASqSdFSP2eC4
The extra transmit power is a huge benefit over FRS, gives much clearer transmission in a head to head test I did last year.
The removable antenna gives you flexibility to run a shorty antenna for convenience when you don’t need max range and a bigger antenna for when you do. For example:
Nice short antenna:
https://www.smileyantenna.com/shop/p/fnw3258zkpt4fld-zrh97-369hr-dnk9h-dxg2a-jdjm8-9m3yy-7nka8
Bigger antenna:
https://www.smileyantenna.com/shop/p/fnw3258zkpt4fld-zrh97-369hr-dnk9h-dxg2a-jdjm8-9m3yy-7nka8
If you buy an antenna for your radio, check to make sure it has the right connector type for your radio.
This guy does some good antenna testing:
https://woofthebeatenpath.com/best-gmrs-handheld-antenna-review-of-nagoya-na-771g/