So maybe this was asked before, but I looked and couldn't find an
answer...

Say you're on vacation somewhere in the continental US and you want to
rent a Skyhawk for a day. Assuming you don't need a renter's policy for
the rest of the year, is there a place you can get rental insurance for
just the 1 day?

In other words, is it possible to get renter's hull insurance for a
plane rental - similar to the way they offer optional collision and
liability insurance with a rental car?