Yeah there would have to be a standardised banner pack as well.
Not only that, but the banners are changed so frequently and new/old ones added/removed all the time that it would require a lot of updating. It would only work if a standard banner pack could be agreed and the person updating the banner pack was able to change this. But a truly standard banner pack would probably require far more stringent rules and quality control than is currently in place with the one I manage in order to keep everyone happy.
Basically I think it would be a lot of work for something that isn't really needed. Yeah it can be annoying that lots of people stack one banner, but it's not annoying enough to warrant the work.
A simpler solution would probably be to add a crpg clan page outside of strategus. If your character joined that clan, you'd have that tag rather than just changing your chars name to include it. Then rather than balancing by banner, balancing could be done by tags. But I'm not sure if this is possible. You'd have to allow alts to join other clans though. For example my main is in GK, but my hoplite alt is in PL.