As noted, comm in JOTR can be extremely limited. If you get lost, you are your only hope. To mitigate that you have to have a plan, and you keep to that plan. Simply wandering around out there is a sure way to becoming lost.
I've done a fair bit of work in JOTR, and have done a well off trail solo overnight hike to Rabbit Peak. It is a spectacular place, but it will not forgive the unprepared.
Having radio comm will be good, but frs is constrained by low wattage and is topographiclly sensitive; any loss of line of site greatly restrictes the radio's usefulness. (I had four mile comm with people in Death Valley - the actual valley north of were most people frequent - because we had good line of site; the moment there were any low knolls in the way, that was it, no comm.
If you plan on being apart in any remote locations, bring USGS maps of the place you plan to explore, have a route planned, and keep to it. Have a schedule for return time and location. These details will greatly assist in being relocated by search and rescue should you miss your return deadline.
When I did my solo hike I planned my route, left notes and details with family and friends, and left a copy of my route in my rig at the trailhead for Park staff should they notice that I hadn't left by the date specified on the permit.
You can download free historical maps from USGS here:
https://ngmdb.usgs.gov/topoview/viewer/#4/40.01/-100.02