Deck/Platform Board Question

I decided to post this here rather than the outdoor board.

I’m building an elevated 6’x6’ wood platform to put a hunting blind on. It will be 6’ tall using 4x4x6 as legs and cross braced with 2x4s.

The “frame” is going to be 2x6s. All lumber will be treated and I will use lag bolts for assembly.

The question I have is about the floor. It won’t have a load heavier than 350lbs (me, my kid, and the blind) and I don’t want to use plywood. I was thinking of using either 2x12s or 1x6s for the floor.

If I use 2x12s will that load be too much for the 4x4 legs? If I use 1x6s, do I need to have a cross support board midway under the floor?

FYI- I will be using these brackets to attach the 4x4 legs to the “frame:”. LINK