I've heard of people with USAA getting covered while at a HPDE event, but it's only a matter of time before there fine print catches up with the rest. You used to be able to cover your *** based on the fact that it was a Drivers Education event but they all now pretty much exclude you as soon as your wheels touch the track surface.
Agreed value track insurance is the way to go if you are concerned about a total loss. SCDA and some others let you sign up for it right at the track.
HPDE Insurance Program