I don't think Pete and Trudy are all that young. The start of the first season was 1960, and Pete was out of college and I had the impression he had been around Sterling Cooper for at least a couple of years then. This season, I think it was 1966. Pete is most likely in his early 30's. And Trudy is all about having all the trappings of upper middle class suburbia, which would have to include a pool.