I've heard on this forum people getting broken into in their own driveway. Storage yards too. It doesn't matter, if they want it they'll find a way to get what you've got.
Inside storage is great but most the time expensive. In the places around us, once put inside it's there until spring as other people are packed around you like sardines to maximize space ($). And price wise expensive. Not to mention battery maintenance. You can't start the generator or MH's to keep the batteries topped off. So it's either remove them or disconnect them. Neither were a option for me.
We've been in storage yards for years without ours being broken into ( others have). But they added barbed wire and cameras. No problems since then. We paid $68 dollars for a back in spot for many years. We finally got a electrical spot. Cost is $81 per month.
Never covered any of the RV's we've owned and they all looked fine when sold. So for us a powered outside storage is perfect. Next best would be at home.