You can do dial peer forking from the gateway to an external recording server.
To do the dial-peer forking your call must be SIP to SIP. Even if your trunk to CUCM is SIP your external protocol is E1.
What you need to do is send your E1 call to a loopback IP address in the gateway using SIP and then a second hop which is SIP from the loop back IP address to UCM using again using SIP. This second hop is then SIP to SIP and can be forked.
I have done a small number of these where the customer wanted to record calls to an out of hours service so no IP phone was in the call path to use the built in bridge.
To answer your question I don't see you would need a CUBE license because you are not running as a border element