After Oct 1 visa exempt entry is 45 days.
Entry by air or land border.
Forget the tourist visa.
Each entry can obtain a 30 day extension.
So eg ...enter by air visa exempt 45 days.
Do one border bounce reenter visa exempt 45 days.
Obtain one 30 day extension to either entry.
All up 120 days.
More if you want.
Edit: just reread your OP. You are only looking for 90 days.
Two visa exempt will cover that.