Use vision pro with Mac virtual display WITHOUT internet?

One of the main reasons I bought an Apple Vision Pro was to use "Mac virtual display" for my MacBook on flights (so that I can have a larger screen and people can't stare over my shoulder at confidential documents).

However, the "Mac virtual display" feature doesn't seem to work without an internet connection. Has anyone found a solution to this?

I have wifi enabled on both devices, and have successfully connected the two many times on the ground when both are connected to the same internet-connected wifi network. On the airplane, with wifi enabled on both but neither connected to a network, I can successfully airdrop, but cannot connect a virtual display. I've tried connecting both devices to the airplane wifi network but without buying internet connections for the devices) and that hasn't helped. Neither has creating an adhoc wifi network on my Mac.

Any advice?