[Elecraft] K3 - Can you set the power level Per antenna?

[Harry Yingst via Elecraft]

In preparation for getting a KPA500 I have ordered the KAT500.
I also have the sub receiver (KRX3)
What I would like to do is to use ANT1 on the K3 to feed into the KPA500 and KAT500.
Then reconfigure the AUX antenna on the SUB Receiver to use the ANT2 port on the K3but I want to ensure that it will not transmit out the ANT2 port ever.
Is there an easy way to do this?

Thank you