First of all one must understand what TSSAA says is not always "gold"
Just because they may say practicing with two teams is o.k. does not make it right.
I don't see the ego a problem, nor do I see the extra practicing a problem. What I fear and what other high school coaches may fear is the chance of injury. I try to go beyond the call of duty to keep my players safe at all times during all drills in practice, so my players may make it through the season healthy. If a kid was to get injuried during a summer league practice (during the hs season) not only would they hurt their coach, but more importantly they would hurt their teammates and the team. This would also be vise versa during the summer.
This is the #1 problem and fear that I have and many other coaches may have also on this issue.. Thanks