I'm not sure what you are asking. Are you looking to get a new contract in a different location (as opposed to actually working out of your RV)? Some types of contract work is fairly common among RVers, e.g. nursing and construction and I would think that IT professionals would fit in as well. Basically you find a new location that has contract work for you and then move to that area in your RV and find a campground to live in for the duration of the contract. You find the work through the usual professional contacts and help-wanted ads.
If you are looking to find work actually in a campground, I'd say the chances for mainframe-type IT work are slim. Few campgrounds have more than a microcomputer and some campground admin software. There may be some work setting up or maintaining/improving the campground's wifi network - that sort of thing is common enough.
If you want to do software development or other IT-related tasks, you can do anything you can do via the internet, including a PC as a terminal on a mainframe system. Obviously you need a strong internet connection to do that, so you probably need to carry that with you, i.e. cellular modem or satellite internet.