The only persons who could get a novel published in a major way would be Robin and Gary. Fred could but not so much. But with Robin and Gary already being known and have had books released; they could. Of course it would be about them more than Howard and it would never reveal any behind the scenes or negativity.

Now who would be able to right a good revealing book that's honest about Howard and the show:

Benjy

He is low key enough and has some external writing credit/connections and doesn't appear to get any flak for fighting back with Howard. So I think he would be unscathed for such a book. Only issue would be if he could get a major release unlike Jackie or Stuttering.

The best for low down and dirty stuff...Sal, but he's a nobody outside the show so he couldn't get a deal, let alone his devotion would have to be totally shattered for it to happen, which hasn't happened yet so it never will.