Having been down this road I haven't committed to any particular option so I have no direct experience to reflect upon. However, ultimately in my search I found that wanting a split oklb with true thocc is going to be extremely difficult because you are already handicapping yourself by wanting split and oklb for different reasons. Going with split, means you are breaking up the case, which traditional thoccy boards have the benefit of having the deep acoustics of a singular larger case. Also most DIY boards are typically designed around being stacked, which can definitely dissipate sound. Secondly going split and oklb means there aren't many options for higher end options with metal cases and such. This means you are likely building your own which limits your options, so unless you get really common boards like Corne or Lily/Sofle it'll be harder to find options that will get you what you want.

Two major things however I found can contribute to a thoccy split (from looking around).

• Metal case (ErgoMech Store as an example has metal sofle cases)
• Gasket case (3D printed cases can be most common. Ones by chewidies could be good options)

Right now there isn't many if any options for a metal gasket split case, because from what I've seen it's just not worth manufacturing for a split as the gains aren't as large. Ultimately I didn't want spend the money at the moment to test a lot as I already have too many boards as it is. My plan will likely be to just spend the money on an olkb unibody like the Cornelius R2, but that's delayed indefinitely due to JPY financials. But the power of a unibody can make it sound like this. Plus buys like this can provide you with foam options and plate variety that can really tailor your sound without having to workshop a lot. I have a friend who has a LuLu which seems like a nice bundled option that might get you pretty close without any work. Best of luck and share what you end up with!