Not many "ultralight gliders" in the US until they built the
SparrowHawk.

There's still more Carbon Dragons than SparrowHawks... nearly 2/1
IIRC (might not all be in US, hmm), but even added together it's still
not many... Gary Osaba knows a great deal about the fine lines of the
sporting code on ultralights if you contact him... Also Leo Benitti
set a respectable one of TX in a too and would know the nitty gritties
and I'm sure would be glad to help if you contacted him.
relevant: http://records.fai.org/docs/9635-4.pdf

His Silent was 281lbs empty for the flight, within D/U limits. If it
were the motorglider version, it would have been 140lbs heavier and I
think out of weight for the category. You should be able to
extrapolate whether Leah and her Cherokee are too fat for this
category or not. If they are over however, I recommend different
verbiage to convey this point

-p