How about the easy way. Hand out a bunch of turnpoints
(easy to see from the air), including some that are REAL close
(house thermals, stuff only 4 miles away, etc.)

Fly to whatever points you want in whatever order and then
make it back to the IP at about normal pattern altitude,
and then do a regular pattern, and land. Then tell
where you flew.

A teenage boy and girl can time releases and landings
from the ground, and get the release altitudes from the
tug driver. Or you can fudge it from the towpilot and
pilot recollections.

To make it interesting, square the handicaps, so use of
lower performance gliders is encouraged. This will get the
PW-2s out there... Make up some rules about release
altitudes and landouts, but don't tell anybody,
and just factor them into the scores (this is about
how it works at a real contest anyway).

An award (Marathon bar) for distance, and one (Jolt cola)
for speed.