Could you use a VPN on the device to make a remote server appear as a local server for network installs? If so, could you loop back an on device “server” through a remote proxy?
So, this is actually how Cydia Extender "worked" (aka, "failed" ;P)--though I wasn't using the Xcode protocol but instead did an ad hoc install (which turned out to also separately not work for non-developer signed IPA files, TWO issues I had failed to notice before release ;P)--but Apple restricts usage of the Network Extension (VPN) API using an entitlement only available to paid developers (which I will strongly assert is to help the CCP's censorship of Chinese citizens as part of Apple's continual unfortunate collaboration). (I now happen to work on semi-programmable VPN tech that is in the App Store, so I might have options; a bit risky, though ;P.)