The easiest would be margin of victory (but you could cap it at 35 in an individual game to take away the incentive to RUTS). You could also do strength of schedule or/and pre league performance.

The other option would be to have either a selection committee (best option IMHO) or polls. Polls could be either coaches or local media. I played high school spots in a different state where only the league champ was guaranteed a playoff spot. Then there were a bunch of at large spots. You had to win a certain number of games to be eligible for an at large spot (I think 13-15 for basketball, that’s what I played). Then a selection committee would seed all of the teams. Utah doesn’t have to go that far ( I actually like Utah’s system) but they could have a committee break ties.

There are lots of things better then a coin toss or fake half games.