What size planks fit 2017 3rd gen bed slots?

Looking to build a bed platform in the bed of my 2017 TRD OR. Anyone know what size size planks fit best? Anybody got pictures of there 3rd gen with a bed platform in the back?

 

I put pressure treated 2x6's in mine last Saturday. I have hauled 6 sheets of 3/4 Oak plywood the other day with no issue. I didn't think to take a picture while it was loaded but with a strap around the back (using the tailgate latch points) and one over the front top (using the bed anchor points) it road great on the interstate. I'm very happy about this because not being able to lay a full sheet of plywood flat in the bed was a big concern of mine.