Uhaul has two different trailers, the silver and the red one. The silver one is wider. I moved a 1971 International Travelall 4x4 with one a while back, so here's a few hints.
1: Lie your ass off. I was towing a travelall with a travelall. There books catagorically deny that International ever made anything other than scouts. Therefore, they would not rent me anything to attach to a travellal. I had to go to a different store, and tell them it was a 3/4 ton suburban. They were estatic about renting me a trailer to tow behind a suburban that said International Harvestor on it.
I also told them i was going to be hauling a Honda Accord. Again, they didn't know what a traveall was, so they could not possibly allow me to haul one. I'm normally a tragically honest person, but I have my limit, and uhail is it. When I told them I was going to haul another suburban they told me I couldnt haul something that big (same with a k5 blazer), despite that travalll being within the weight limit (Ok, it was 5 pounds over)
2: Check the straps before you leave. Our trailer had a bent ratchet for tightening the strap, and the previous renter had cut the strup to release their vehicle. We found this out when we were in the middle of nowhere with a bohemoth of a travelall on the trailer already and we had to stop at a truck stop and get a set of ratcheting tiedowns to mcgyver a strap extension. Which brings us to three.
3: stop on the way and check the air in all the tires on the trailer. Between the strap issue, and all the tires being unevenly inflated the truck/trailer rig was weaving all over the road like a fidler crab on PCP. We cleared off three lanes of trafic, and it took a year off of my life. i still have nightmares about it.