The two tow planes I maintain have different ADS-B out. On one I installed a Stratus ESG transponder. (The original transponder had failed.) The other tow plane I just installed a skyBeacon.

My preference if it’s my airplane is to install an Stratus ESGi. That way you have a new transponder with both in and out. The tow pilots can pick up the ADS-B in along with AHRS and weather on their iPads.

The uAvionix tailBeacon will not work on a stock Pawnee rudder FYI.