No, I think you do want them close together, your previous idea of keeping them 1 1/2" apart would be ideal. I was thinking if 2 pallets nested completely tightly together, then you would lose the gap. ON the style in my link above the legs fit into each other so you could control the gap by putting something in the hole that the leg fits into to adjust the gap to 2" or whatever gap you want. That would work well.
Bill Cody taught me that some shiner species need much tighter gaps, almost better described as crevices. They need gaps more like 1/4" or so.
