GREAT IDEA about renting the dolly first! You might hate it...but your Mazda Tribute will love it (front wheel drive not 4x4* - right?) - no miles on the transaxle and no modification to the car. The Tribute is almost a duplicate of the Ford Escape (a very common toad) and will tow very well.
You will have to get a tape measure to find out what drop hitch you need because RV's vary the height of the tow receiver...and dolly's vary the tongue height too. If you rent from U-Haul they can sell you the right drop hitch or you can call them to find out the tongue height of the dolly. A Drop Hitch is not very expensive.
Best of luck!
*If your Tribute is 4X4 be sure to double check the ability to dolly tow.