Tiny,
I asked State Farm about the deductible and about total loss and about stated/appraised values and about depreciation. I trust their answers.
First, before anyone starts the insurance company bad-mouthing (most of which is well-deserved), I have sadly had to deal with two total loss accidents (one with a death) and State Farm handled both better than I ever might have expected.
With State Farm, the deductible that you want on your old vehicle(s) must be the same (or more) than the deductibles on you regular vehicle. This is a very clever rule. I can get 0% deductible (in NY) but it is REAL expensive. Hagerty is 0% deductible on an agreed-upon replacement value (non-depreciated).
Also, with State Farm, if you have towing coverage on your regular vehicle, you will have towing coverage on the old vehicle(s) (even a 2-ton 20+' platform bed). This towing coverage is nowhere near as good as Hagerty's add-on towing coverage (125 miles).