Your overall point is well-taken, Dan.
However, Black Hawk, Marshall & Melrose-Mindoro are not top-6 teams in the state (per MPZJames), regardless of division. Undefeated D-3 Laconia (26-0), from the always tough Flyway Conference, is another excellent, lower-division team.
I'll stick with my top 6, with no apologies:
1. D-2 Beaver Dam (25-1)
2. D-1 Mukwonago (24-1)
3. D-1 Milwaukee King (21-4)
4. D-1 Bay Port (25-1)
5. D-4 LaCrosse Aquinas (25-1)
6. D-1 Kimberly (23-3)
There are better smaller school then your top 6 schools.
To compare apples to apples where some of the top teams got a chance to play each other, this last summer pre-season at the 2018 Wisconsin Varsity Invitational your ranked #6 D-1 Kimberly enrollment 1589 students was beat by D-5 Black Hawk school enrollment 99 students; score 58 Black Hawk - 48 Kimberly.
Black Hawk went on winning the next game in the tournament to advance to the championship game against Beaver Dam. Black Hawk eventually lost 49-67 to beaver Dam, but for the first 8 minutes of the championship game Black Hawk was winning. As a side note Beaver Dam was missing one of their starters for this tournament but because of their great depth it really did not hurt them at all.
If it was not for this Wisconsin Varsity Invitational tournament Black Hawk would never had received the chance to play the schools they did: New Berlin Eisenhower, Kimberly, Appleton West and Beaver Dam; all having much larger enrollments. These bigger enrollment schools usually have nothing to gain playing the little schools. If the big schools win they receive no recognition for beating a smaller school because it was perceived that the bigger school should have won the contest before the game even started. If the small school wins the big school gets downgraded no matter how good the competition was that they competed against. It’s basically a no win situation for the big schools when playing the smaller schools.
Because of this perceived outlook it is very hard for smaller schools to schedule competition against the bigger schools. For the most part big schools will not schedule games with smaller schools that have a chance of beating the bigger schools.
In my opinion this is why when the question is ask to list the top teams in state the smaller schools usually fall short of this list and are not mentioned. They never get a chance to compete against each other.