My dad did something like this a few years back, not at a fence but over a beer. He told me he wanted his headstone to just say "he was kind" and nothing about his 30 years at the phone company. That one stuck with me too, and what helped was actually writing stuff down. I made a little list of the things I do that have nothing to do with work, like coaching my kid's soccer team and calling my mom every Sunday, and just seeing it on paper made me feel less weird about it. Your uncle sounds like a solid guy, and honestly the fact that you're still chewing on this 3 weeks later says something about you too. Maybe next time you see him, tell him you've been thinking about that list, I bet he'd get a kick out of it.