If you have a full clan, then you probably have up to a dozen co-leaders, correct? What happens if the leader breaks his phone/tablet? What if a co-leader needs to be kicked and the leader hasn't been around? What if two co-leaders don't agree on something and the leader has a broken phone?
Those are just a few examples. We all know that there are thousands of clans that give out co-leader as a recruiting tool, which devalues the position. If there's only one 2nd in Command though, then that gives the clan something more than a recruiting bonus position. Each clan should be allowed one 2nd in Command who can kick co-leaders, elders and members and who can only be promoted/kicked by the Leader. In the even the Leader leaves the clan (to help a cousin or whatever) then the 2nd in Command automatically assumes his position and nominates a new 2nd in Command. Basically, the equivalent of a President/Vice President.
I've been saying this. I have one CO who really helped me build this clan from day one, would be nice to show a little appreciation and recognition to that person by giving them a step above the other CO's.