A summary of many of the prior threads on iRV2:
1) A Toad Charge or similar device is not necessary.
2) A wire from the toad connector to the battery should have a fuse or circuit breaker in it, as close to the battery as is practical.
3) One fellow who installed a self-resetting circuit breaker at the toad end of the charge line had a car fire that destroyed the front end of the toad. A fuse or non-self-resetting circuit breaker should have prevented the fire.
4) On rare occasion, a diode is needed in the charge line. It prevents the toad from sending 12V to the coach. If you find you need one, you can install one.
My toad has a Duo. I installed it, along with a Toad Charge. At the time, I did not know point 1) above. Later, I found that my coach was one of the rare birds that needed a diode, point 4) above. It happens that the Toad Charge provides the diode function, so I had the answer before the question was asked- sorta like Carnac the Magnificent
Either the charge line works well, or the Duo draws less current than one might think, because my toad's tiny 340CCA "motorcycle" battery has never been dead after more than 20,000 miles of towing.