Every carrier is different so I am not sure. The AEV carrier must have had some bushing or something that isolated the swing our part from the rest of the bumper, thus not having much metal on metal connecting the two peices. Looking at pictures of the evo setup it looks like the hinge pin is isolated from the tire carrier with a thick rubber bushing. If you could figure out a way to mount the antenna to the cornor armor you would probably be good to go without a grounding strap (as long as you paint the skins and not powdercoat them). They come unpainted so you could weld on a tab with a 1/2 inch hole before you paint them and call it day

 

The corner armor actually has tabs right above the tire Carrier mounts to run a cb so that's where my antenna will go. I will be powder coating though so I guess we'll find out in about a month how I'm going to ground it. The AEV carrier sits in a spindle housing mounted to the frame directly

 

the powder coating on the stud will isolate the stud from the metal on your tire carrier. You will want to run a grounding wire from the stud to a metal ground in the tub of your JK. You don't have to scratch the paint anywhere but you will need to ground it on something other than a powder-coated surface.