I don't think the BIM, State Or Corp of Engineers will have a montly rate most Ive been to you can only stay 7-10 days at a time then you need to leave and be out of the park a day or two then depending on availability you may get back in for another week to 10 days and start over again. Alot of private parks have a monthly rate and some have your electric on a meter. If your not using they don't charge you for it. If you are going to the area for work it may be tough but some parks may have Work Camper jobs where you work some hours at the park for reduced or possibly free rent. Good luck