PaddyT,
You dont mention your budget.
If you want a combo unit, we have the Garmin Rino GPS/UHF radios here, and for the sort of use you are talking, they would be perfect.
I think our models here are the Rino 650; the current equivalent is the Rino 750.
5 Watt Handheld 80-Channel UHF radio.
Colour screen GPS, with the option of downloading Birdseye satellite imagery, and overlaying your maps over the satellite image.
It has a MicroSD slot for additional maps.
You can buy a spare battery pack that uses 4 AA batteries, so if you cant charge the Li-Ion battery, you have a plan B.
If you have 2 or more, they can share their positional info between the units via UHF 'Chirps' (Only works on non-repeater channels)
Not cheap($730) for the Rino 750, but depends on what you are looking for.
https://www.ja-gps.com.au/Garmin/rino-7 ... -handheld/Probably way more than you are budgeting for, but the Rinos are pretty much everything you are looking for, and then some.
Cheers,
Rod.