...and one more thought... You might want to make sure that it isn't the water at the campground. We had a similar problem a few years back when camping at Turkey Run State Park in western Indiana. Turned out that the the sulfur smell was coming from the local supply. The local folks had grown used to it, but for us, it was quite annoying. Took a couple of tank drains and flushes of the plumbing before it completely went away. We still camp there on occasion, but now we fill our FW tank with our local water before we head out. Might not be your problem as it sounds like you've stayed at this campground before, but thought I'd throw it out there anyway.