The only reason I didn't see Bruce as Carmichael was that Carmichael is described as short, overweight and balding.
I think the problem we're going to run into here is the descriptions. Jim is very specific and fans notice when actors don't match the description given, which is why, in the long run, I think it would be best for the show to be animated, and the characters voiced.
I tend to get really annoyed when fans put too much stock in a character looking exactly as described in a book when adaptations roll around. Certainly it makes sense when appearance is
relevant to the character, as I would argue Harry and Murphy's are down to most of the details (leads always tend to have their looks be more relevant to their character, what with being the leads), but, say, Carmichael? I'm looking for kind of a narrow-minded, lazy cop/general turd
attitude more than any particular look (though admittedly short, fat and balding are cultural shorthands that work like a charm for that) when casting that part, at least for initial appearances. Bruce Campbell could swing it well enough, though he's generally too charismatic, I think, for us to dislike him.