I am trying to find a successful recipe for frosting swirls on cupcakes to be used for weddings in the very tropical South Pacific. Royal icing pipes well but sets too hard. Buttercream softens too quickly if not refrigerated. Any ideas????

A b/c made with hi-ratio shortening will definitely hold up better than a b/c made with Criso.
(I'm sure a butter based b/c would be out of the question for those temps.)

Sugarshack's hi-ratio b/c recipe:

http://cakecentral.com/recipes/5163/sugarshacks-icing-and-tips

However, if all you have is Crisco - Indydebi's recipe will hold up better than most:

http://cakecentral.com/recipes/6992/indydebis-crisco-based-buttercream-icing

HTH