Before telling Oldsport that I didn't think his proposed rig would be "too much," I thought about asking him what the other guests would probably be wearing. Then I said to myself: "Ah, forget it. It's not a job interview where his career is on the line. It's a family birthday party. Nobody will be judging his choice of clothing--and if anyone does do that, so what? Let Oldsport be a role model. Then some family members, years from now, might say, 'Yeah, Uncle Oldsport. Always a dapper dresser, that one. I learned a lot about clothes from watching him.'"
Birthday party on July 4th at 6 p.m. for a relative? Don't overthink the clothes. Just have a good time.