Yup I was thinking of doing a channel down the center, I may lower the overall high of the box by lowering the top plank sides down so there's no gap between the top and bottom plank sides....maybeMan, those tiller bars are really long! I agree, they may be better served on a more stretch style build. But they are very cool!
I love the 'sunken crate' idea. One idea would be to cut it down the middle lengthwise, mount a regular bike rack on the bike, and then hang the two halves on each side so they line up and look like a complete crate. Then in the back and front, add your cross slats so they match up and give it more of the box look.
Looking forward to what you come up with!
cRaTe oN~!