If you have the setup as you have wrote and i understand it, then all you need is a RCA wireless transmitter.
I use this to get signal to my outdoor sub.
Add wireless audio connectivity to subwoofers, speakers, amplifiers and more. Transmits pristine audio signal up to 65’ at CD quality.
www.svsound.com
just plug one transmitter into the zone 2 RCA outs on the TX-929NR and the other transmitter into the RCA of the subwoofer outside. Just be careful, transmitting distance can be limited.
There should be no need to do anything with your current zone two speaker wires. Leave them going from the TX-929NR to the klipsch.