Aye, don't think any of these crowds pull less than a half-full field, and in the case of Fender, expect him to be notably stacked.
We're not in for an enomo-headliner crowd, a la Elton John last year or Coldplay this year. But all three won't look like SZA in the dusk, I'd wager.
Just to add to the comments above I think you’re massively underselling O-Rod too - I’m 44 (not 20 something) and of the three she’s the one I’d like to see the most.