I'm in the same process of selecting a box for a coyote built, based on researching i think you will get three responses. Interested to see it confirmed though:
For all three options do the frame re-enforcement, and you will need the additional plate to move it outward for the coyote.
1. If you want to stay stock buy a used box for 350-400 and send it to wcb for 150, use a flat rate shipping box. Stock holes would be correct for this or the one linked to from WH. This box will be at the upper end of it's capacity at 33" and you may experience shorter than desired lifespan
2. Do the 4x4x2 conversion and save compared to the linked WH link, strongest kit out there, it will require either making a notch in the cross member or drilling a crooked hole otherwise. It also will require 1 additional hole. It will be putting much more force on the frame so make sure it is reinforced
3. Do a Borgeson kit for a little more affordable option then a stock WH unit and potentially a little bit stronger, but not a full rock crawler setup. This is a nice setup but for the same price as the 4x4x2. Less frame modification potentially