What about Totino-Grace? I think they "should" be 4A by enrollment. I believe they "opted up", but would be criminal for them to be 4A or 5A.There really should be some sort of competitive evaluation that takes place with the bigger schools (6A and 5A). If a 6A team is getting blown out all the time or struggling with numbers they should be moved to 5A. A dominant 5A team should be moved up to 6A. You could look at it every season and maybe give teams the option to move down if they meet certain criteria.
But that is a pipe dream because it would require someone to really do an honest assessment of teams and people would almost certainly complain about it and feel it wasn't fair to their squad.
Setting the classes based on school enrollment is the easiest way to do it, but the competitive balance at 6A is not great right now and there are a lot of bad teams at that level.
Similar thing should be forced upon SMB.