Do the coaches from your region actually meet to discuss All-Region? Do you have the ability to trumpet the cause of a player on another team?
I'm not sure that's the case with all regions in the state. I have a feeling that spots are allotted based on how a team finishes in the region standings. Then, it is solely up to the coach on who represents their school on the all-region team.
I've experienced it both via coaches voting (cannot vote for your own) as well as allotted spots based on finish. I prefer the latter.