Ok so this is a lot to take in but i will try to give a few or two cents.

1. Love the idea
2. Veterans or VoS = Veterans of steem tag would be easy to sue and simple.
3. Bots work off action/inaction members names would have to be added into the bot in order to suggest who is or who is not. Some bots like Ginabot can already notify based off tag or keywords so that would help and it works with discord even better.
4. Curation of vets in a community environments is awesome, soon hopefully steem will release the communities update which will simplify this entire process and make the group able to be searchable with shared rewards members only and so much more.
5. In the meantime a single tag, and the discord i think is the best path forward to reach said goals.

Lastly - I will guard my post from flank to flank and not take shit from any rank.

Salute!