Good luck in your search, Nik. It's worth the effort.

Keep in mind that you will have to be added as an additional insured
pilot on the glider owner's insurance policy. (Being an SSA-sanctioned
contest, there is absolutely no way around this.) Getting added means
submitting an application to the insurance company that covers the
glider, and you remain on the policy for the remainder of the policy
period. If that period is less than some number of months, the
insurance company will require a renewal, usually to stretch it out a
full year from the effective date of your being added to the policy.
And of course the owner of the glider will require you to pay the
difference in the insurance cost.

This is not as difficult or expensive as it sounds; I flew my glider as
a team with another pilot at the 2005 Region 9 Sports Class, and we had
to add him to my policy first.

Good luck again and don't give up!

~ted/2NO