yes, I have not, but know of dozens in my area who do. Actually I did keep a Model T pickup in offsite, storage.
Points to ponder for the least expensive, such as just plain storage areas you see on the sides of roads, etc. Typical car space = about $2-300/month secured access and doors.
1. climate control: Typically no power, and they won't allow heaters in closed storage. Some offer cars sites, with extras like heating etc.
2. Mice/rodents: Typically a good site has pest control, but you'll want to set more traps anyway. They'll wreck wiring etc. quickly.
3. Covers: Can get those $300-1k+, instant inflatable 'garages' to help your storage issues, but simple dust cover suffices for most.
4. Dampness: Easy fix. Can't remember the name, but you can buy it by the envelope or bucket size. It extracts moisture above a certain dew point: check home depot...quite common...REALLY good when you spill water in the trunk or such as it'll suck the moisture right out of any area quick as can be....it's magic.
5. Fire protection: Good luck, only a certified car storage site has this. Using the cheap [mentioned above] approach will mean whatever you get. I've seen 2nd story units with protection for common storage, but doubt you'll get much for your dollar.
6. GOOD LOCKS: I have, for a simple investment, used great locks, hack proof, pick proof, and you give the site an extra key, just in case...they are typically bonded and good idea for if you lost yours, it's very expensive to get that repaired [cut off, re-done etc.]
7. longer terms can be a better price break
8. Unless you absolutely know someone you can trust, don't share a site, get your own: Loose lips and all.
9. Make sure your insurance company guarantees your coverage in an off-site, area: Consequences are not good for fire, theft, damage, flood etc....might get a rider.
10. Tell no one 'cept your closest, or perhaps even the owners [typically unless a car site, they don't care] what you are storing there, and make 'clandestine' egress both to/from.....people, thieves to be exact, know these places and do scope them out.
11. IF long term storage, either disconnect battery or plug in tender. And I mean over a few days for yours as well: Resetting the ECUs and such is a pain in a 360+ car. IF YOUR car fob looses power, then YUCK. Might want to keep a window cracked
12. IF long term, think of FULL tank of gas, premium, with a stabilizer: Might not want water to accum in brake lines too = killer to systems especially since one has to get an ODB II reader to refill oil, brakes, etc. etc.
now I know there are better, more costly, sites that specialize in car storage. They might be your best bet.
Like I said, many I know, and I'm talking in the $100k+ cars, keep them in simple storage, but, they know a lot more about the security going on in there and all the points I made above....one would be truly amazed at what lies behind some of these benign looking boxes on the road
Guide to the Galaxy: Don't Panic
Rik -- LAH !
1990 Mondial T Cabriolet SN 86247 : Red/Tan
1995 456 GT 2+2 SN 99987 : Roso Metalizzato [Fer 311/C] & Tan