I did a rally race in South Carolina earlier this year and called everywhere, no one covered it.
NASA Rally Sport league was hosting the event and had $1MM medical coverage for participants, including air lift and all the bells and whistles you'd want if you wrapped a tree. They required a full medical be done locally (not covered by OHIP). Once done, I e-mailed the forms to the league Dr. who reviewed and approved it. Without it I couldn't race.
See if Glen Helen offers something you can purchase from them?