To be honest, you might as well just go with the standard Wifi clause on, that is what this generation and the past has ran on, what Showdown uses, what PO uses, so I feel like if we just enabled it there would be less room for people to complain. Plus if it really comes down to it, there are other tiers to ladder on. One might argue that the other tier might go unused. This applies to almost all tiers, and especially to servers who don't get thousands of new users every day like main does (Finding battles outside of standard OU can be complicated).
Some are considering a ticked option to use Wifi or not. But then again, is it really a ladder? I doubt it would be a fair #1 if people had to fight against unfair odds in Wifi ON/OFF
Coming down to the point, I say implementing it for the main ladder, and leave another tier for NO Preview. Therefore the options of the players aren't nearly as limited, and people could battle on their prefered ladder.
Feel free to tell me if I'm missing something here, I'm quite new to this server.