Gliders without adsb must conduct operations

(1) Outside any Class B or Class C airspace area;

(2) Below the altitude of the ceiling of a Class B or Class C airspace area designated for an airport, or 10,000 feet MSL, whichever is lower.

You can request ATC permission to deviate from these requirements; " For operation of an aircraft that is not equipped with ADS-B Out, the request must be made at least 1 hour before the proposed operation" (91.225g2).

I doubt that this one hour requirement would be strictly enforced in a land out situation!