Is AfterM*A*S*H bad enough for the OP?
How bad does it have to be to be that bad, though.
For instance, Joanie Loves Chachi, which I saw 1-2 episodes of, perhaps, and After M*A*S*H (same) were each considered pretty bad, but may have suffered from being int he shadows of the super hits they were spinoffs from.
Klinger was funny on M*A*S*H, it seems easier to do this with the se4quel/spinoff than it does with Joanie Loves Chachi, which I don't remember at all.
So, Klinger - instead of having PTSD or whatever-related troubles (I don't recall what but he wound up in the psych ward of the hospital Potter worked in from what I read) - decides he's going to overcome the demons that impacted him. Out of work, the first episode centers on him dressing in in drag and trying to do stand-up comedy in a nightclub while Potter becomes like Newhart in how he helps patients; he's no psychiatrist but finds himself shoehorned into the role when something funny happens to the last one.
So, Potter is facing these challenges from patients both mental andphysical, while Klinger finds himself bombing on stage. It's so bad int he opener tomatoes are thrown at him, among other vegetables. The commercial break comes as someone comes up and dumps a whole pitcher of water on him - "I didn't have anything solid" he explains after the break.
Klinger is flummoxed. He'd lived life making people laugh in the Army as a way to get through it, and figured he could do it in the U.S., too; indeed, perhaps he even relied on Potter's advice of "doing what you know." He goes to Potter to discuss it, and learns there's a lot more to making people laugh than he thinks. Potter reveals - much Klinger's surprise - that he, too, is feeling like a fish out of water as he serves in his new role. "I could understand you," he tells Klinger, "in my heart I knew what you were doing. Some of these people..."
In the end, Klinger decides that comedy might be for him and winds up trying to study for it, while Potter actually gets some insight from Klinger on how to help one patient in particular, which impresses Klinger a lot. Maybe he can even help in that field.
Okay, so that's the opener. As for the rest...
Potter and Klinger become the kind of duo you had a lot of in the early '80s and before - Hardcastle and McCormick, for instance. Potter tries to understand psychiatry and learns how to relate to some of the people in a Newhart-esque role that, admittedly, some people think is stealing from Newhart itself. (Bob even makes an appearance in one memorable episode as a psychiatrist, which is said to possibly tie the universes together, though viewers who say that are like me before this edit and forget the show took place in the mid-'50s.)
Potter also ends up helping Klinger as the latter tries to learn how to do show business. As Klinger tries to find his niche, he ends up actually helping Potter some as well as the colonel deals with different things, although at times it tends to go toward the "Wesley saves the ship" trope it doesn't quite go there, which saves it. ANd, of course, Klinger also deals with funny situations at the school he's studying in under the GI Bill.
I don't know if this is enough of a classic for you, but I think this would allow AfterM*A*S*H to become a success for 4-5 years. Where they went wrong was focusing on the problems just like M*A*S*H did. Yeah, maybe Klinger would have problems after returning home, but it's just as likely he was very intelligent in what he was doing and in fact would be a future comedian. And, if they take the character that way I think it'd be better.
Frankly, though I didnt' see anything beyond the first episode if that, if what I read is true I suspect they wanted the irony in one scene of people thinking Klinger was crazy and didn't realize it would destroy the rest of the show; a show that had begun pretty lame anyway. But, you could have something else ironic instead. 20 years after Korea, perhaps Klinger makes it into Hollywood and is starring in a sitcom about a psychiatrist. he could be that universe's Newhart, with some of the ideas from his days with Colonel Potter after Korea.