I'm not sure I understand your point; if exe.dev operates a dedicated IP solely so a specific mythical IPv6-less developer can connect to a specific server, then there's no tunnelling involved at all.

Oops, I think I mixed up two sentences in the middle. A fixed comment is available. But I also probably misinterpreted what you were saying:

> they could pay a small extra for a dedicated IPv4 address.

Did you mean that the dedicated IPv4 address to connect via SSH? Then my objection doesn't apply.