One major issue -- don't forget security. Unless one has real security, a RV place will get broken into all the time. Cameras are useless -- they might get a picture of a blob, or if in HD, a vague outline of a guy with a balaclava on.
Electric is nice -- a 15-20A plug combined with two Battery Minders (one for the engine batteries, one for the house batteries) will keep the batteries usable, even in extremely cold weather. Metering is wise.
Rates should be set similar to other places. Here in Austin, $100/month will get you a spot. That's it. Other places, $100 might be way too high.
A wash station is a nice thing -- I would use it. However, they can be expensive since in some areas (like Austin), the runoff can't drain into the sewer or storm drain, so has to be pumped out.
Similar with a dump station -- would be nice to have 2-3, because just one will always be in use by someone who will spend hours rinsing their tanks out.
Indoor storage would be very nice, especially heated/cooled (doesn't have to be perfect, just above freezing in winter, below 85-90 in summer.)
The main thing that I am concerned about when it comes to RV storage is security. I'm less worried about stuff disappearing than the damage a tweaker does. A TV is not too expensive. Trying to rebuild an inside wall after the unit was yanked off its mountings can cost thousands, most of that not covered by insurance. The best security I've seen was not just dogs running around, but two security patrols. A guy with the truck, and a guy on a bike, both armed with lethal and non-lethal items. The meth-heads see the guard in the truck and hide, but bicycles are stealthy, and much harder to listen for.
