You want to go to a business that actually install trailer hitches, that specializes in welding and metal work. I did a quick Google search: Chicago, Il, trailer hitch install and it returned 304,000 hits! So there are places in your area that install hitches. Look for a welding company that installs trailer hitches. They are out-there.
I would not wait on Camping World any longer. If they couldn't give you the information you needed upfront and negotiate an appointment right away, then go somewhere else. And by the way, the BEST welder hitch servicers I've found are the mom-and-pop shops, and NOT the big bang organizations.