When I worked for an outfitter we used Sink the stink, dipped the life jackets and all the gear (booties, wetsuits, splash jackets) at then end of every day in a cattle water tank that we filled fresh with new solution and hung them on the back porch to dry. Then we moved them indoors with huge fans moving the air around. The gear smelled great for all the use it got, but it was a ton of work for tired guides. If life jackets stink really bad, I'd first use soap (dish soap, Doc Bronners sal suds, or simple green, whatever, as long as it is soap) to soak the jackets, scrub off any spots or stains with a scrub brush, then rinse them in clean water. If you don't remove the oil and dirt first, it's going to be harder to get them smelling good with anything else. Follow the soap with vinegar or sink-the-stink. I think sink-the-stink is supposed to be an enzyme cleaner that breaks down crud, but it's pretty mild, so frequent use is probably the best bet.