I have already laminated 1 layer of fiberglass on the bottom of my board, but I want to add the "football" shaped patches to support my that area. Can I still do that over the first lamination?
Yes you can add football patches over the first lamination. Normally they are placed on the foam and laminated with the bottom layer at the same time but no worries, it's just a but more work.
Just sand down the edges of the football patches after they cure so there is not a hard edge. When you hotcoat you want the surface to be smooth and the resin to flow over everything uninterrupted.