Congratulations to the happy couple!
Jeep rentals tend to be a specialized, niche business. It's easier to rent a lLamborgini or a Ferrari than a Jeep.
Assuming your boss's son wants a Jeep Wrangler, and not a Cherokee, or a Patriot, you will have a tough time trying to find one for rent at the local Jeep dealer or Hertz.
That said, it doesn't mean you should not try, worst they could say is 'no'
You could also try here:
I also rented one when we went to the Great Smoky Mtns in Tenn. here is their link:
Good luck, and remember, women cry at weddings, men cry after...