bolt bed to frame under wood?

[gulffishin]

I have taken the wood out of my bed and am getting ready to put in the new wood. I was wondering if it is safe to bolt the cross sills to the frame using short carriage bolts under the wood using only the bottom holes (bolt not going through both the top and bottom of the cross sill). I am worried that the bolt could eventually wear through the hole and cause the bed to come loose while driving.

If I am going about this wrong, how do I go about hiding the bolts that hold the bed to the frame?
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