our intention is for communication to the outside world, not really between cabins or vehicles
Ham radio will probably allow you to communicate from your cabins to your home in Riverton, depending exactly where each is located. At the cabins, you should be able to hit both the Ephraim repeater (146.660) and the one at Boardinghouse Ridge (147.080). Both of those are part of the linked Sinbad system, which also has a repeater on Lake Mountain that offers coverage into most of the Salt Lake valley.
If your Riverton home cannot reach the Lake Mountain repeater, it should definitely be able to hit the 147.120 machine on Farnsworth Peak, which is part of the Intermountain Intertie linked system. There is another Intertie machine down on Levan Peak (145.270) which you can probably hit from your cabins; if so, there's another option for you.
A more fun option would be to try and sneak a signal through a mountain valley. This is heavily dependent on the precise location of your cabins, but if you're lucky you might squeeze between a few mountains and get a signal to one of the repeaters on West Mountain just outside of Payson (about 45 miles from your cabin). If you do, that machine will also reach up into parts of the SL valley and may let you talk to home without using a linked system. Or you could go for a
real trick shot and try to bullseye either the 70cm repeater (449.950) in Vernon or the 145.390 repeater on Black Crook Peak. These machines are ~ 70 miles away, so it'll be tricky... but it would be neat to "bank shot" your signal from there into Riverton and to your home (depending exactly where it is).
Please note: all the above assumes the use of a mobile ham radio with 50+ watts output combined with a good 1/2-wave antenna. If all you have are HTs, your likelihood of successful communication over these distances is substantially reduced. But even if you are limited to HTs, it can't hurt to try and experiment. I'd even be willing to assist you in your testing if you like.