Are you running with an established group? What are they using?
Are you just wanting trail/convoy comms? Or "reach out and touch someone" comms?
There are still people/groups that run CB, while some are making the switch to GMRS. Even Jeep Jamboree has moved to GMRS, it is far better than CB...
I use one during the local VHF contest where I operate as a roving station. Furthest station that was participating was just over 40 miles and I didn't have a problem working him on 5 watts.
(old picture, old Jeep)
I made one, it was pretty easy and the pin outs are the same for the 2900. But by the sound of it, the Mobilinkd isn't what you are looking for.
As noted it doesn't function as a dumb tracker, only as a more fully featured APRS set up with display and messaging and such, really more along the...
An oddly shaped ground plane can distort the signal as it is pulled in the direction with the most metal.
With the roll bar being tied to the rest of the body it may not effect it too much, I also wouldn't worry about it too much.
Also with the soft top, if the antenna fit with the top up it...
Can you get inside the roll bar to run the coax and secure the NMO mount?
Here is another option for a 1/2 wave antenna (no ground plane): https://www.amazon.com/gp/product/B00IDTJ2KE/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
A front fender mount would work well also...
I imagine having access to the Colorado Connection (linked repeater system for those not aware) has a bit to do with the adoption of ham radio in your area?
As dreadlocks mentioned, the radio service used by groups/clubs does seem to be regional.
A ham radio HF antenna on the outside should at least help, though not optimal.
Maybe a 75m hamstick and a Wolf River Coils Silver bullet 1000 would get you about as tuned as you are going to get with a "short" vertical antenna (relative to a long wire antenna tuned to the AM frequencies)
Antenna height is key for VHF/UHF.
When working the repeater the antenna is a couple hundred possibly over 1000' in the air giving it a much greater range.
Simplex (person-person/vehicle-vehicle/person-vehicle) the antennas are 6' (+/-) off the ground and with the curvature of the earth you will...
If you are ok with the overall height a 1/2 wave (on 2m) antenna could be mounted to the rack as it is not ground dependent.
A fender mount on the driver side would work also, though it may not reach quite as far.