There's been so many car clubs with the same name (shifters, deacons, pharaohs, lords etc...) through the years. The minor similarity between their logo's should be a non issue. I could see if they were in Nor Cal or San Diego, but they're way the fuck in Wisonsin. I seriously doubt they'll get confused for each other.
However, Common Courtesy dictates that since their club (coffin chasers) are better known nationally, you should contact their president and run it by them to see if they have an issue with it.
Of course you could just say fuck it and let the cards fall where they fall. I doubt there will ever be a confrontation. But saying "Fuck those guys" is a sure way to create a problem in such a small tight knit community.
Just one mans humble opinion.