Not that this is the place for this, but:
Because it's a violation of FCC rules. GMRS radios are supposed to be FCC certified specifically for GMRS. Amateur radios are designed for Part 97 services, not Part 95.
MARS modification can also negatively effect transmit power and reduce signal quality.
I used to have that rugged radios antenna mount, but switched to a Mountains to Metal mount due to the same problem (antenna bases not fitting). I have an antenna switch in the cab to switch from the 3db bull at antenna to a 6db a pillar antenna in that spot. Then I also have my HAM antenna...
Added a couple solar panels in prep for the trip to the Big Bends in a week.
Might have to order another panel and another pair of crossbars, looks like I could get three up there, easy.
I used these:
https://www.undergroundgraphics.com/products/ford-bronco-spare-tire-tailgate-bumper-extension?_pos=1&_psq=spare+tire&_ss=e&_v=1.0&variant=46617103433967
You may need them when you upgrade to the hinge reinforcement. (I have the Turn Offroad adjustable tire carrier and tailgate...
Used these mounts from Amazon (https://a.co/d/07w3Jtoy) to mount the RTL-R to the back facing side of my Trailrax TRMR roof rack, had to space out the mounting bolts a bit more than recommended to allow enough room for the Alucab table to slide in.
Oh yeah, plenty of wire. I was able to run the provided chase light side all the way up under the dash on the passenger side, mounted to a Turn Offroad flasher module, and then to the ford white wire that runs into the engine bay for the accessory switches.
Brake light side was equally long, but...
Added a Baja Designs RTL-R Chase light bar to the rear of the roof rack, and some Monster Hook Rock Ring recovery points.
Shout out to @4x4TruckLEDs.com for the light bar and exemplary customer service. I bought a light bar from them and a custom wiring harness, that made it so easy even I...
I doubt there was much of any drag on them being on the roof, since there was a taller rooftop tent right behind them. Mounted on the rear, I don’t notice or see them at all.
I used to keep mine on top of a trailrax roofrack, just in front of the rooftop tent. I have since moved them to an American Adventure Labs Spare Tire Platform, and only cary them when I'm going out somehwere.