I've been invited to a wedding in May and the bride has ask me to wear my kit - but it's going to be a California casual affair and a full formal Prince Charlie isn't called for -I'm a guest rather than a member of the wedding party. Also, the wedding is in California which I expect will be pretty warm. Ergo, an Argyle w/waistcoat is also probably going to be a bit much. Perhaps even a necktie is too much.

Any suggestions on an assemblage of parts to look nice without the kiss of Formality?