Will Ndproxy work on a tunnel interface?

Should this be working if ipv6 is on a 6rd tunnel interface? Since the tunnel interface doesn't have its own mac address, I'm not sure what mac address to enter.

I tried the physical interfaces mac address, but that didn't seem to work.

[bsdlme]

Here's a forum post in which somebody writes that it works for him using a wireguard tunnel interface:
https://forums.FreeBSD.org/threads/ipv6-proxy-ndp-not-working.56696/post-622445