IPIP Tunnel configuration with DHCP address

I could use some advice. I’ve been trying to figure out how you create the IPIP interface when the client RB751 is a DHCP client on ether1 and is assigned a dynamic IP address.

When creating the IPIP interface, how does one assign the dynamic address to “local-address” when it is not known until connected to the network?

Pointers much appreciated!

Regards