With the newer connection groups, the hookup_connected and hitch_connected animation variables should be able to specify a hookup (like part_present_X), that way you don't have an airdrop harness visible when you're just towing it on a flatbed.

Fixed in V20.0.0.

I can do this, though it'll break all existing animations as they'll need to specify the index. Is that a problem?

Not for me, but it might be for Kadwin and Laura

They seem to be okay with this. So I will change it. Flagging as bug as it's technically one. However, note that this will be per-group, not per-connection, unless that's what you want.

Per-connection would be more robust (think lockers for different trailer hitches like a fifth wheel or ball or different towing connections), but per-group would work fine.