You want to find a welding and fabrication shop in your area. I doubt if any of them will build anything without seeing the MH first and taking all sorts of measurements. You'll also have to take the bike to them at the same time so they see and understand everything. I'd talk to 2 - 3 of them on the phone first, then take things to them to them to get an estimate. Take a day and make a trip to three of them.
I Googled welding fabrication shops in Yorkville and there seems to be several that can do the work. I don't know about your area, but if there are any steel boat fabricators, look at them also. They're usually very good at fabricating custom projects.
Bill