My hangar is on the county airport, hence a land-lease. However, USAA covers the hangar as "other structures external to the residence", with a limit to 10% of the policy value, but that definitely covers the value of my hangar. If it were valued above that amount, currently ~$70K, I could elect to increase that percentage for additional premium, or get a separate policy. (my old hangar is not valued above that, so I'm good to go).
It's important to note that it does not cover anything that would be considered an aircraft or aircraft part, but it does cover the structure, tools, furniture, and of course the beer fridge...