Was playing around with a drawing editor last night and came up with this. Still has 8 boards even if they are similar to dimensional lumber at 5 1/2. If I can get them wider it will be even tighter. Will have ability to expand and shrink with temp.
If I can't get them wider I might have to make a bushing for the strip bolts so they don't crush the strips, but that is not too hard.
I am undecided if I will through bolt the boards to the frame in stock locations, or if I will secure bed to frame and hide those bolts under the decking.