I adapted this recipe from a camping cookbook, Simple Foods for the Pack, by Claudia Axcell, Diana Cooke and Vikki Kinmont. Originally almost all the ingredients were dehydrated (except for the canned crab) so that you can just throw them all in a ziplock and heat them in camp with water. This is probably a great idea for OAMC, but this recipe is also very fast to put together if you haven't made it ahead. I had it on the table within half an hour from start to finish, and that included time to cook the potatoes in the microwave.
This chowder is very rich even without any dairy in it, and obviously you could make it vegetarian without the crab.