Just for the information purposes of others that may have the same questions, I do not agree with emptying the tanks as you want as much weight as possible, as low as possible...
I would empty and flush gray and black, then fill all tanks with water and the tub also, then I would leave and head to a hotel...
Under no circumstances would you want to be in an RV during a hurricane...
I stayed on our boat (46' sport fish) in Key West Bight (A&B Marina) during Charlie about 10 years ago. You haven't lived until you have been on a boat with a hurricane approaching! I really don't advise anyone doing this either...
This really doesn't appear to be much more than a typical summer storm for us, however if the rangers can't get you packed up, I can go that way with my 2 boys, each 21 years old and do whatever is necessary, including a place to stay at our home in Tampa.
And Thank You for your service to our country!