I say he invents a new cooking technology and with all the money from that he weighs 425 lbs from non stop eating. He also invents a self opening-self closing refrigerator. He also hallucinates his long deceased FIL telling him to get away from the refrigerator and from Archie's "little goil."
shareDidn't he become a teacher in the series?
Then he ran away with one of his students/Homecoming queen to a commune?
He would have spent a few years there then either get burned out on that lifestyle or it would have broken up then he would have moved back to a city or large town and gotten another teaching job.
Retire from that and live off the pension.
The only other option I could see him doing was making a living off of skills he learned at the commune.
A small scale organic farm or something in the trades such as plumbing or solar power panel installer.