It makes little sense to me to spend the money for a campsite with electricity (if you can find a campground that lets you store the unit on a site while you're away for that length of time) or an indoor storage facility rather than learn how to winterize yourself. It's not like you'll never have need of winterizing and dewinterizing in the future, and it's really not that hard to do though it can sometimes be a bit time consuming. You shouldn't need to undo the enclosed undercarriage, nor need much in the way of tools.
The water heater is drained by removing the drain plug; this needs a wrench or channel lock pliers, and is done from its outside access panel. The water tank is drained with a drain valve, and the interior pipes mostly drained with low point drains. You may need a pipe wrench to open the low point drains if they're just pipe caps on nipples, but more common is a valve that just requires turning or pulling manually.
If you're winterizing by blowing out the lines with air, which is what I do, you do need access to an air compressor (with a regulated outlet, preferably) and appropriate fittings to attach it to the city water inlet. If you're using RV antifreeze, you may need a bit of tubing or a funnel or some similar odds and ends, depending on the specific setup of your RV's plumbing system.
There may be instructions in the owner's manual for winterization. There also may not be, as far too frequently the manuals are generic to the point of being nearly useless.