With a rental car you would have an easy time provisioning at the nearby Pueblo and filling in some treats at Gourmet Gallery in Crown Bay Marina just as Rick suggested - going to CostUless would be worth the effort if you have a big group but know that they do not have bags - usually there are empty boxes of various size available - [don't load corrugated cardboard onto the vessel] - if you have any big canvas bags, a cooler or purchase some of their insulated bags it will be much easier to load and unload.
Packing some of your favorite seasonings is a good tip - the liquid refreshments are bulky so make sure there will be room in the vehicle, likely better pricing than dockside delivery.
A good detailed list will also save you time and money IMHO.