jQuery Help With jQuery PLugin Default Options

[gilgimech]

I'm not sure what's wrong, but I can't get the default options to work in my plugin.

Here's my Code

(function ($) {
    $.lilRWDMenu = function (el, options) {
        var base = this;
        base.$el = $(el);
        base.el = el;
        base.$el.data("lilRWDMenu", base);
        $.lilRWDMenu.defaultOptions = {
            mainMenuClass: 'main-menu',
            rwdMenuClass: 'rwd-mobile-menu'
        };
        base.init = function () {
            base.options = $.extend({}, $.lilRWDMenu.defaultOptions, options);
        };
        base.init();
    };
    $.fn.lilRWDMenu = function (options) {
        return this.each(function () {

            var mainMenuObj = options.mainMenuClass,
                rwdmenuObj = options.rwdMenuClass;

        });
    };

})(jQuery);

I'm not sure why but all the variables are coming up as undefined. I've written plugins before like this with no problems, but for some reason it's not working