I believe this is the same model the Aging Wheels guy on youtube bought, and then the inevitable happened. You could desulfate the batteries, but he stuffed it full of custom lithium cell battery packs instead.

You are correct that using lead-acid in this application is a really bad choice. Even deep cycle batteries will have a crap energy-to-weight ratio. This was the result of the manufacturer (or more likely Home Depot themselves, who specified the product) to rush something, anything out the door to jump on the bandwagon as fast as possible. You see this shit coming out of China all the time, like the little "neighborhood electric vehicles" that in their stock trim leave the factory with like two lead-acid golf cart batteries in the back that give it a range of approximately eleven feet.