Get reliable players, and finding out whether they're that or not really shouldn't be overly hard, and if they're not, too bad.
I agree that should be possible. But in practice, thats not how it has worked.
Magistr Honna and MortonHQ were very dedicated players. MortonHQ dissappeared from our clan with no warning whatsoever. The same thing happened with Dracovious, who up until then was very active. We knew that Honna was going to have a time where he couldn't play, but it crept up on us without us realizing and he didn't give final warning.
For Tiger's clan there was Vixen who dissappeared. The Devs all got busy but they at least warned their clan.
For FoR, there was Zakuwa that dissappeared without a trace. For the RN, they had a few players leave suddenly, including Arebane, a Marshall at the time I believe.
Where do these players go? I don't know. They don't tell us.
I still haven't seen anyone refute the idea I presented earlier:
A battle has a 5 day turn limit.
If the clan leader spots one of their players going over 3 days, they reassign a new player and inform the clan war admin and a new battle is created with a 3 day limit. The same clan cannot reassign a new player after that point.
If the clan leader didn't notice the battle in time, its their fault for not keeping up on the status of their clan's battles (which can be easily found from the tournaments section of the main MA page BTW). The admin has very little to do, about the same as they would when declaring a new attack. They change some names, cancel a battle, and create a new one when a clan leader sends them an email.