Try it before buying it.

Updated info
Per U-Haul rentals there dingy's do NOT have brakes
Per Penske rentals there dingy's do HAVE brakes.
Rented a U-Haul before I knew this and went on drive North of Phoenix area and the RV handled towing up grades just fine. However did have a pucker moment during a braking event.
IMHO If the dolly had had brakes the pucker factor would have been greatly reduced.
Have decided to go ahead with purchase of a Acme tow dolly with surge braking.
In the near future will be able to tell the difference between brakes or no brakes for a dingy for my application.

I had a dolly; an old DEMCO Kar Kaddy. Like a dummy, I sold it.
I plan to get another one before next summer.
I definitely want to take a vehicle with us.
The truck is too heavy to tow.
the ATVs are street legal, and I have a trailer for them, but for long touring they just are not practical!
that leaves the PT Cruiser. It is an automatic tranny, and I do not want to cut holes in the front for towbar mounts, so a dolly is the only way to go. I towed it from here to Georgia and back on a dolly, so there will be no surprises.

The little two wheeled dolly from Harbor Freight that is used for moving trailer around makes moving the empty dolly very easy!

Just my thoughts.
U-Haul does rent them but they are very heavy duty.
Many that we would buy are light to medium weight units.
I did not like the dolly that I bought as it was nearly impossible to back up with. I sold mine years ago.