We have stayed at both El Requezon (Bahia Concepción and Yax Ha (Chetumal) and enjoyed both. Our favorite in Yucatan (and almost anywhere) was Laguna Azul at the north end of Laguna Bacalar. We could get in with a 28' TT but didn't try last time with 34' 5th wheel. We were headed for Belize/Guatemala and were in a hurry but will try next time. There are no hookups but there is a water point and a dump station. They provide free kayaks.
We met folks from New York (traveling by bus but staying in one of the cabanas) who said it was the best birding they knew in Mexico/Central America: Toucans, Collared Aracari, Emerald Toucanet, Yucatan Jays, the ever present and noisy Brown jays.
Some friends drove down to Laguna Bacalar from the place we love best on the beach above Tulum and saw a Jaguar, just the way one wishes to see one: in a car, on a decent road and the engine running. It was a Smart Car and a Jaguar being a cat, might just decide to play with it and roll it like a ball and toss it in the air for play!
Reed and Elaine