I have used U-Haul trailers for years to move bikes around. Due to the low loading height I found it much easier to load than putting a big bike in my pick up.
Consider renting a covered trailer, they are the same price. If you get caught in bad weather, your bike stay clean and dry. The other advantage to a closed trailer is that if you stop for the night, no one knows what's inside, and you can lock the back.
The downside to renting ANY U-Haul trailer is that you cannot lock the trailer tongue to your draw bar.
When I picked up my Rune last summer I used a 5x8 enclosed trailer. The bike BARELY fit. I would recommend the 5x12. It has a tandem axle and tows much easier.
With respect to the 45 MPH limit, I think that is "lawyer speak". I have towed their trailers at 70+ with no problems.
Another trick that I learned is that you can use soft loops through the wood bumpers to keep the rear end from moving.
Good Luck-
Duane