When going east to west, we stay between 20 and 20 when crossing oceans and only do the tropical storm belts in the offseason (your run from Panama to Marquesas is not in the belt). Between 20 and 20 there is only one place I know of that gets winds over 35 knots (not including tropical storms) and that is in the southern Caribbean near Santa Marta called the Colombian Low. If you do that after Sept and before December you will be fine. The problems arise when getting in hire lats. The run to NZ can be very bad if picking the wrong window so that is why NZ sailors fly to Tonga for Blue Water festival week to give classes on how to plan and do the trip.