Anybody know if is is
common for the towing models to be able to release the line?

Darryl

Yes, I've done several Aero Tows with models, always have a servo that
can release the tow line at each end, just like full sized planes.

In the East Coast and Midwest they even have meets for model aero tows
with very powerful tugs hauling up 3.5 to 4.5 meter models of ASW's
and such.