Your right karch, I didn't think about it in that sense. The haystack would indeed be just like the trees in CM, every turn they are randomly plopped down in their square of scattered trees, woods, tall pines, etc. It would be eye candy, but it would be nice to see them sprinkled about if you use a farmland map.
Another thought, use it as you would a single grid square of tall trees or woods. There could be a few haystacks shown in that square, a square that vehicles could drive through like scattered trees. You could setup ambushes from the haystack squares, but like scattered trees, vehicles can and will be spotted relatively easy. I know that LOS passes through scattered trees unhindered, but I think the LOS through the haystack square should be similar to that of woods or tall trees.
I'm probably way off base, but its early morning here and I am pretty tired. Thanks for the responses guys.