Man I have the in-laws from hell so I know what you're dealing with. Same problem, when they visit it's like non-stop activities and I don't want to spend the whole time with them. They're like supercharged tourists.

Fortunately my wife feels the same way and doesn't force me to participate in every activity. But if I didn't participate in some then like you say, I'd look like an asshole. My wife does what she can to give me space so it's tolerable. I do dread when they come to visit though. It's the polar opposite with my own relatives, we can lounge around and talk for hours in a relaxed way, it's very easy going.

I rely on my wife to provide some insulation, maybe that's something you could ask of your wife. If my wife didn't do that for me I don't know if I could tolerate the in-laws coming to camp out for several days at a time.