To me there is nothing more frustrating then spending hours making a roster and then recieve a no match and be left waiting untill the next war. This is just a thought but after the matchs are made,what if the clans that got the no matchs were given a small amount of time i.e. 15 mins, to change their roster to match the other clans who also recieved a no match.
Support for the idea of changing no matches. Another option could be have match round 1 where the normal match happens, then match round 2 where none matched clans to choose to war each other in spite of not matching. I don't know how they would do it, but if both clans agree to war anyway that could work too
Say that it is a 20 vs 20 war, each clan has 25 members cast, and then the last 5 to cast are reserves. That way, if there is no match the players will be automatically switched out with the 5 reserves to match an opposing clan. Just an idea.