Insurance companies aren't giving tons of coverage on salvage vehicles for a reason.
Surely you'd agree a salvage car is worth inherently less than a clear title in even in identical physical/mechanical condition. Cosequently, ins. co's are going to pay out less for them.
The advantage, however, is that YOU should be paying less for a salvage vehicle versus clear, thus limiting your financial exposure if you wreck it, which reduces the need for higher ins. coverage.
Which makes me curious...how much over "clear title" cash value did you pay?? My point is, you shouldn't NEED high coverage.
BTW, most, if not all ins. companies do offer ins. on salvaged vehicles. You'll have to poke around a bit to find one that offers more than the rest. Try State Farm. They're a little more expensive, but coverage is usually very good, and service is better than average.