The antenna for your Sirius XM is on top of the roll bar, so no worries there.
I just grabbed the first Prime next-day stubby that fit the JL/JT and ignored it after that.
They still ask me at my carwash about mirrors and antenna, I just nod and go.
Edit to add, this is the one I bought, there are MANY like it: https://smile.amazon.com/gp/product/B00651CLCS/
Here is the link to the US Amazon site
Definitely get him a shorty antenna, it'd look so good, only $20 on amazon too. http://www.amazon.com/AntennaX-Off-Road-13-inch-Antenna-Wrangler/dp/B00651CLCS
I highly recommend this one. No signal issues. Had it for a couple weeks now. Pretty cheap for a Jeep mod too.
Surely. I was wrong about the price though. It's $17.
A small/subtle/inexpensive addition I made as soon as I got mine was this guy:
Get yourself a good wax that's easy to apply on your own and some good micro fiber towels. Makes all the difference in the world.
Also some of this:
Works great on all the plastic pieces that get beat up by the sun.
(for a JK)
Interior:
* Rugged Ridge type dash tray organizer thing
* cup holder/trash can thing if you have a 4-door
* center console armrest pad
* roll bar handles for passengers
* floor mats that trap dirt/moisure
* inexpensive speaker update?
Exterior:
* smaller radio antenna swap?
* people seem to love taillight guards?
(I don't like the look of tons of external mods, so I don't have many to list)