Glider cross-country time toward commercial SEL requrements?

I'm trying to determine if any of my glider cross-country time can be
applied to the commercial single engine aeronautical experience
requirements.

FAR 61.129 says "50 hours of cross-country flight of which at least 10
hours must be in airplanes".

FAR 61.1 defines cross country time as, among other things, flight
with landing beyond 50 nautical miles of departure and "conducted in
an appropriate aircraft".

I've talked to a local examiner, FSDO, and Oklahoma City. All are
saying, "Hmmm, good question! Let me get back to you".

Anyone with experience with this question care to weigh in?

Thanks,
Matt Michael CFIG
Woodstock N20609 "Wanders Wonder"
IS-28B2 Lark N28DG