For towplanes the critical case is below and to the front as sadly shown in this TSB Canada accident report:

https://www.tsb.gc.ca/eng/rapports-r.../a19w0099.html

While the student and instructor were wearing parachutes, the canopies were still on when they hit the ground. I suggest the brief be "When you hear my canopy coming off, get the hell out NOW!"

Of course a Flarm can't ever help when it's not on.

An external antenna on the bottom of a glider is highly vulnerable to damage in outlandings and getting in and out of the trailer.