We carry hull coverage on our stuff, but it is and has been much smaller than that. PT-19, L-19, T-6, T-28. That part has never been a problem for us.
I can see how a bank may hesitate to finance a warbird because of the huge range of values on a given type and strange issues with type certificates, and the general fact that warbird operating is sort of "off the beaten path", as are the airplanes.
talk to your own bank. They may have more options than you think. It may be that it requires more collateralization than a typical airplane loan. But then again, I don't know much about money or how to get it, only how to spend it.