Are you getting that $400/week price around your area?
Full-timers travel. There are many wonderful small town areas, national forest, national parks, state parks, city and county parks that have rates WAAAAAY cheaper than what you quoted.
Of course, not all are full-hookups. But then you're self-contained so you really don't need full hookups.
We're at the Albuquerque Balloon Fiesta and staying 12 nights with no hookups. It's easy to do.
For future questions you might want to post on the full-timing forum. In the meantime, scan that forum for many answers to your questions.
Full-timing doesn't have to be expensive. We've done it for 16 years. :)