Clan Wars opt out

Have an option to specify whether or not you will be participating in a clan war so if you won't be active you aren't taking up a space someone else could have.

Example, I'm leaving on vacation for a week so I set myself to "clan war = no" and for that week any clan wars started won't include me. When I get back I can set myself to "clan war = yes" to re-include myself.

Just leave the clan and rejoin when you return.
Or, lose all the trophies you can to be the lowest in your clan