Appreciate it's your first RV but if you have good battery bank, and are comfortable being off grid, there are tons of options for boondocking that would give you and your fur babies lots of space. Arizona Trust Lands, Bureau of Land Management, Wildlife Refugees (check dog status on these), USFS - Forest Service, and many others.
A great resource we've used in past years for our daughter, fiance and their dog was BringFido.com. They RV'd and when in Chicago found some awesome restaurants they could bring their GSD.
This is quite a good link for checking out more far and wide for future reference: https://www.tripsavvy.com/of-the-bes...-parks-2912407
Enjoy and Happy Travels.