i had 5 gallons of diesel in my bilge last winter from a failed tank. tried every cleaning product known to mankind with no joy in getting the smell out of everything inside the boat. It happened over the winter so the diesel just sat for months unnoticed giving it a serious chance to work its smell into everything..
After cleaning it all out and flushing the bilge several times with dawn/simple green/pure ayre, and then cleaning everything in the cabin, the ONLY thing i was finally able to get the smell out with was, believe it or not, essential oils.. i picked up one of those nebulizer style vaporizers.. i ran cinnamon, tea tree, rosemary and lemon oil mix with every door, cabinet, floor hatch and cushion propped up to all all sides to get treated. i ran a fan to move the air around and nebulized 1 fl oz of the oils inside the boat with the doors and windows shut.. i let that sit for 3 days and then opened everything up for fresh air.
the diesel smell was gone. and what was left was the best smelling boat i've ever been in.. in fact, it stayed fresh smelling through the entire summer. i'm planning on treating the boat again like this in the spring.