For two golf cart batteries, you're going to need a considerable amount of solar to keep them charged, if you're using any significant portion of their capacity and relying on the solar as the primary charging source. As a (very rough) rule of thumb, consider one watt of solar for each 12V battery capacity amp hour as the bare minimum - and double that if you want to give your batteries a fighting chance of a decent lifetime.
So for two GC batteries, you'll need at least 220W or so of solar, and 400 would be really advisable.