Ham Radios are king for trail communications. The ideal set up would inlcude a mounted "mobile" radio and an "HT" (Handy Talkie or hand held radio).
My personal radio set up consists of 2 mobile mounted, dual band radios and 1 or 2 handhelds at any given time.
...yes it's overkill, but I run APRS, monitor 2 repeaters or FRS channels and still have a channel left for local group communications on simplex.
FRS Radios are useful for those not licensed in ham radio. The signal clarity is much better than CB and a pair of these can be purchased for less than $30.
It is recommended to keep plenty of spare batteries on hand or find a radio that includes USB charging so a 12V / USB charger can be used in the vehicle.