The covers of the AC units are very thin plastic. Then tend to break easily. I would put the Kayak on a side mount to one side of the AC unit. There are many different Kayak mounts which can attach to the cross arms between the two SS Cabin railings. Thule and Yakima both have mounts which can be adapted--or make one out of thick PVC pipe for the least expensive solution. Schedule 80 1 1/4 PCV pipe (or electrical conduit) is plenty robust. Some T's, 90 L and 45 L , add in some hose clamps, and PVC glue--maybe paint it a color to harmonize with the strip on your boat to give some UV protection and "Bling".