ADFS Proxy Replacement on F5 BIG-IP

NPolitis, no, not a simple way. It may be possible with some iRules but the official supported method would continue to be two virtual servers. This also provides you with troubleshooting flexibility you probably don't want to lose.

You can deploy them at the same destination IP address however, and use the source IP constraint on the VS page for the internal load balancing only virtual server, though. You'd constrain it to your internal network, e.g.: 10.0.0.0/8 instead of the default 0.0.0.0/0. You would need to make this source address adjustment manually, outside the iApp with strictness disabled.