High quality bunkie board for king latex mattress

Hi. First off this is the best forum ever. I used this site a decade ago to buy my first latex mattress and it was life changing.

We have recently purchased a king latex mattress. My wife and I are a combined 400lbs.

Our bed frame is a steel frame with three horizontal steel slats.

I believe we need a bunkie board as our frame will not support the slat platforms our mattress manufacturer sells since there is no vertical slat.

Can anyone recommend a high quality solid bunkie board, not slated which would support the weight of our mattress and us?

DIY is not an option.

Very much appreciate your advice.

When I went to VISpring, they had a bunkie board. Call them.

John