I don't think my MH even knows the toad is back there! I've never checked the fuel mileage with and without the toad, but I don't think it could be making much difference.
We went with the ReadyBrute towbars with built-in ReadyBrake and saved hundreds of dollars over other products I looked at.
My total cost to get set up for towing was $2032. That included the tow bars, supplemental braking, base plate, toad wiring kit, and complete installation.
I would definitely recommend getting set up for towing instead of renting a car. If you do much traveling the cost of car rental would soon pay for the towing setup and I would NOT want to have the hassle of car rental!
Good luck, happy trails, and God bless! :B