Some 13 years ago I was towing a Blaník L-13 with a Pawnee from 92A to KTHA some 8500 feet North of Chattanooga.
No transponder...

I was so high because the cloud cover was really low and I wanted to give options to the glider if the rope broke (they do break sometimes).

I called Chattanooga approach and advised them of my altitude, heading and intentions, and they handed me a transponder code that I rejected with 'negative transponder'.
And I was advised to stay clear of the class C airspace which I was some 5-10 miles away.

And I kept going in my merry way...

Some 5 minutes after that communication I heard this deafening roar (over my engine) and glanced over the mirror a regional jet narrowing missing the tail of the gilder.

Remember, this is a 200 foot-long aircraft!

I immediately got a call from the screaming glider pilot (over another radio):
**** DID YOU SEEEEE THAAAAT!!! ****

Hell I did...

I never told Chattanooga about the episode and I never knew if the jet pilot(s) ever saw us, but it was a sobering experience.

I have also seen airplanes some 50 ft away from a hanglider while I was desperately circling steep turns trying to get their attention.

See and avoid....