Les would have sold out for Wisconsin. The lack of sell outs or TV ratings have nothing to do with independence or being in a conference. It has everything to do with winning.
However, I'd concede that a byproduct of independence is that all the toughest games are front loaded. If the schedule was flipped and BYU started 8-1 or 7-2 before playing these last 4 games, the feeling would be a lot different going into those last few games. More tickets sold and more eye balls on TV