Coach-
Based on your explanation, what about this scenario:
A district has two "good" teams and two "bad" teams. The "good" teams play a competitive schedule and do well and the two "bad" teams play a less competitive schedule and they still end up losing games. The "good" teams play each other in district play and one team barely beats the other. The other teams end up losing and/or forfeiting their games because they don't have enough talent and players to play for all kinds of reasons: injuries, eligibility, tired of losing, etc.
Using your rating scenario, let's say you end up with this:
Team 1 - 225
Team 2 - 205
Team 3 - 30
Team 4 - 20
TOTAL: 480
If I'm not mistaken, Team 2 will be "out" of the playoffs because of the lower cumulative score of the division.
It doesn't seem fair for Team 2 in this scenario because they tried to do everything right in their control: scheduling a competitive schedule, winning games, etc. Instead, they are now critically dependent on other district members to play competitive games and to continue with their schedules. This seems to open up the potential of bad relationships between schools, especially if one school has a good team and the other school prevents them from getting into the playoffs by "quitting" the season prematurely.
Consider this, too: Team 2 is being penalized twice: once for scheduling division teams who forfeit games, which lowers their power ranking; and the second time for a low cumulative division score. All of this for simply being in a particular district -again, still something they can't control.
Why not let it be based on the team's rating on its own, without the additional factor of this division cumulative score system?