It has been my (painful) experience that RVs have three real big enemies:
Weather
Critters
Disuse
If you do build such a barn, make it so it is 14' under the roof, has a 12' wide door and can accommodate is 45' long. You might choose to upgrade, or maybe the next owner will use it.
It should have 50amp, water and room to work around the coach because you may upgrade and you will at least want to be able to get into the storage and wash it in there.
There is no way you can make the barn critter-proof (trust me on that one), but you can try any and maybe all the things to discourage them from using it as a home.
When the coach is in a barn (as mine is most of the time) and you can keep the reefer cold, tanks full and empty as required, the impediment to using it disappears and you can suddenly fire up and go to (you get to fill this in) on very little notice.
From Syracuse, I can only think of about a dozen places in easy striking range, but we don't like in the east anymore.
(Build the barn, but you might want to find out what you have to do to keep it an agricultural shed for tax purposes.)
Matt