I've done this. I towed my 1996 XJ behind a 1987 Tioga Arrow 24ft class C mini-motorhome. We used both a tow dolly as well as the tow bar setup. I have only one word to say about both.. BRAKES!!! Gotta have an alternate braking system. Something like the BrakeBuddy
http://www.brakebuddy.com/ is a quick and pretty easy solution. You can find these and similar units on Ebay fairly reasonably. A new one is pricey, usually around $1000 unless you find a good sale.
I towed on a tow dolly, with no options for adding brakes and it really put a stress on the brakes of the motorhome. Plus, you add another 300-500 lbs of weight that is now also depending on the brakes of the tow rig.
Two summers ago, my club was meeting another club in Mountain City, TN to ride some trails. We were going to make a week of it and decided to flat tow the XJ to Myrtle Beach, SC for a few days then we'd go on to Mountain City. The drive to Myrtle Beach should have only been a few hours from Atlanta, but turned into 12 hours due to having to stop and start and not being able to get over 30 MPH because my Rusty's Track Bar broke right at the weld. It was a real mess, to say the least. He sent me one overnight so while my family was enjoying the beach, I was under the XJ replacing the Track Bar. Little did I know that my Rusty's Frame Track Bar Mount had also broken, or at least cracked. The entire trip to Mountain City and then home again, was plagued with a violently shaking XJ, anytime a bump in the road was hit. Pretty scary.
On the way back home to Georgia, we came through North Carolina. Every steep downgrade we went through left my wife and kids closing their eyes and gripping door handles because we were being pushed hard by the XJ. Too much for the brakes and even lower gear on the motorhome. My inexperience at towing caused us all a lot of fright! Had we come to one more steep downgrade, I would have had to unhook the XJ and had my wife drive it behind us on it's own power. We would have done that previously, but we had a caliper strip on us in Mountain City and I was worried about the stress on it using heavy brakes on the steep downgrades. It was funny that one autoshop was at the bottom of the largest mountain we came down and had a school bus sized sign out front that said simply "We do Brakes". No better location could they have found for this
Aside from not having an alternate braking system and having aftermarket parts break on us, flat towing was not a problem. A newer motor home with better brakes might not have such an issue. We also did about 5 MPH uphill with the pedal to the floor due to the weight of the XJ on the back end. That was with a 460 CI engine!
In Georgia, the law states that anything over 3,000 lbs being towed must have an alternate braking system. I am sure that other states have similar laws.
I just purchased a trailer, WITH BRAKES, to carry our XJ around. We'll use it for the first time this weekend as we travel to Tellico for the SFWDA Summer Convention. I am looking forward to having help keeping things slowed down from the rear.
Sorry for being so long with this. Just wanted to give an accurate account of our experience with the setup you were asking about.