those should do the trick, but they might slide down some if you take a tumble, but they are breathable which is needed. I use these, as they offer more side of knee protection but do warm up the knee area more. Trade off, after 10-15 min I don't even feel them there.
http://www.bikebling.com/SixSixOne-R...-rage-knee.htm

PM me when you get down here, I'll show you a few trails, most will be a 15-30min drive from the beach but are worth it.