Grundy and Hagerty are more of a classic insurance...I have both...extremely tight on usage and storage of vehicle. You're not going to get a $150/year premium on 30k replacement for something that moves a whole lot and intentionally gets damaged. Chances are, if you don't have something that just sits in a garage, you won't be getting covered. But I will say, it is pretty easy to get coverage through them, if that's the case. Get an appraisal, with receipts, you can pretty much get the number you want. Submit a few pics...and in a couple days you should have a coverage. Hagerty has been great on both my claims...one was Christmas decorations falling out of an attic on to my tailgate...paid for the $600 NOS tailgate and $500 in paint. I also have coverage on my NOS and 'not gonna find them' parts. Had one of my sheds broken in to and had some high dollar NOS stuff taken, and I was reimbursed once I found them again.
That said...I've been catching wind that Chubbs Insurance is an agreed value, and muuuuuuuuuuuch more lenient on use...not sure if they're offroad lenient, but might be worth giving them a call.