[BigLew]

"I'm going to try it around the chase where the fuel vent and gas fill goes."

FWIW- If you do that, ask yourself objectively what do you gain verses assuring yourself one nightmare of a job when (not if) there comes a time that you will want or need to replace the fill and vent hoses? This would be just one question for starters.

Another more general question would be, How will it affect air circulation and venting of gas fumes in the event your fuel tank develops a pinhole leak due to foam having been used to wedge it in its comartment in the hull." On this topic search this website regarding tank replacement and you will find many, if not most, were caused, at least in part, to foam holding moisture in contact with the aluminum tank with corrosion of the aluminum being the result.

Just my CAUTIONARY (as a friend) 2 cents. Good luck.