I also live in michigan....just a few tips i've learned....
it seems the places i called had a different price for vehicle that were 35 feet or less, vs vehicles that are over 35 feet. If your's is like my new bus, 36 feet long, just tell the storage place it's "about 35 feet". That seems to work well. I also ask if they have storage available for my motorhome, rather than my old bus.
Quis custodiet ipsos custodes (who will watch the watchmen?)