If you only want to remote-unkey CT (courtesy tone) on Echolink but want to retain that for Allstar, I think you can accomplish that by tying Echolink to 1999 and then 1999 to your main node. I think this is better anyway as drive-by drop-in Echolink connections don’t pop out on your system unexpectedly.
But do yourself a favor and do not use 1999 for the private node number.
You might find yourself unable to connect to someone else who is using that number for a private node number. It’s a popular number for this stuff. It’s a connection loop prevention.
Make it arbitrary, perhaps a favorite 4 digit number. 1040? (if you are a tax agent HiHi) https://wiki.allstarlink.org/wiki/Private_nodes