I think many poster are missing the point that the OP is riding in TROPICAL heat and humidity.

T--R-O-P-I-C-A-L.

No rain cape/poncho or breathable fabric will help you. You will get wet from the added sweat a jacket/cape or WOOL BASE LAYER(!?!) will bring, over heat and have a fricken' stroke by the side of the road.

I have ridden in hot, humid conditions where I have prayed for rain.

Your feet will get wet but good booties can help.

The trick is to shave your legs and to wear low cut (ankle cut) socks that do not protrude above the elastic at the top of the booty. If they do they will soak up the rain from your legs and release it inside your shoes.

They will keep your feet drier and, more imoportantly, reduce the amount of grit that would otherwise accumulate in your shoes.

Post ride make sure you pull the liners from your shoes and pack the inside with newspaper to dry them out for the next day.