Minimum priorities of physical unit are: [UHF/VHF]
battery power (more AmpHr better - with weight considerations) & fast charge ability (as lithium or alkaline batteries are a weak point); Transmit 'power' (8 to 10 watts considered adequate high power) and transmitter's mate high quality antenna with line of sight and the receiver's receiver sensitivity with the antenna again; water-resistant (unless in a plastic bag - not h20 proof); NOAA weather good to have; other lesser impacting things...
Have a plan on channel usage with respect to frequencies predetermined. For example: A (primary), B (if 2 or more channels/frequencies can be monitored), and C (backup on the odd hour) & D (even hour if all else fails). Find out if local ARRL/ham folks have a repeater frequency(ies) available for emergencies, with antenna on a nearby mountain.
Or if you have a base camp where you can set up a repeater with a big high antenna and have battery backups for overnight charging. A 2nd battery for each walkie & an extra walkie for replacement. For example the BAOFENG GM-15 Pro has a repeater capability & more.
I know I said KISS and went long winded.