Are we insane?

You might look at the California Delta as there are many RV parks and some allow full time living. Cost for a space would be less than a house; however, you will need to factor in the new truck and fifth wheel toy hauler. As this could be a good learning experience on what you eventually would want in a full time RV, purchasing 'pre owned' might save some serious money. Commute to Sacramento is about a half hour to forty five minutes depending on your destination. No way would I purchase a home for only two years especially if the housing market cools off, again. Also, don't forget you will likely need an endorsement on your driver's license if you intend to tow a heavy fifth wheel. Lots to think about.