When I'm concise, I'm misinterpreted, so I have to end writing more… The last couple of ideas were just alternatives for if people prefer them. Personally, I think I prefer the Target Area idea, which is what is described in your link, but only for fighting. My proposal generalises that idea to resource gathering (including hunting), garrisoning, boarding, and even repair, along whatever I can't think of right now.  

Помощь оказывают врачи с практикой в наркологии, психиатрии и восстановительной терапии. Подробнее - москва вывод из запоя

You post so many ideas that I'm getting the reflex to skip your posts, just so you know you might want to be more concise. What you are describing here will be implemented next release : https://gitea.wildfiregames.com/0ad/0ad/pulls/8525  

There's an Issue for that on itea: #4581 (current title: Flags for all garrisonable buildings and units).

Funnily this was a topic on Reddit 16 days before OP as well: