A possible solution would be to have the PF ignore a constant close-
in, almost same altitude threat (i.e.the glider) after a reasonable
period of time, say a couple of minutes. After staging, this would
have the tow plane PF start to ignore the glider's Mode-C either on
the take off roll or early in the climb. Additionally a software fix
might be tied in to the aircraft type and function only if the "tow
plane" option is menu selected.

I've contacted PowerFlarmUS re. this and some other suggestions and
they are responsive. I wasn't meaning to do an end run, but rather
wanted input from others to confirm if what I'm experiencing is indeed
a problem needing addressing. The seperate issue of tug and glider
transponders interfering with one another while on tow has no fix, I'm
aware of, other than leaving one transponder in standby for the
duration of the tow.

bumper