Last year we sailed about 70 per cent of the time with a poled-out headsail and 30 per cent of the time with a spinnaker. Having a coloured sail makes life more enjoyable when the wind drops and prevents you wallowing around, but unless racing you will probably be wanting to drop the kite once the wind gets much above 20 knots true and before that if the sea state is rolly.
We bought a new sail for our crossing – probably not one that would immediately spring to mind: a fairly high-clew 110 per cent jib. The smaller sail with a high clew sets much better when poled-out and gives great visibility underneath it. Deck-sweeping genoas may be faster upwind, but do tend to give a large blind spot which is particularly worrying at night when short-handed.
A maximum sized sail you could fit will spend most of its life partly furled and will quickly lose its shape. Once in the Caribbean and reaching from island to island a smaller sail is much more use and does not scoop up water when waves cross the deck.
I would be very reluctant to make a crossing without a spinnaker pole so as to have the ability to pole out the jib as it is an easy and quick sail combination once the wind