Der Alte, I think that where the supposed nature of Gehenna is concerned, its possible meaning in the New Testament is going to come down to a matter of overall Hermeneutical method rather than simply one that is decided by whether some source is credible or not.
Besides, even if your source is credible---and I think it is----the simple having of one credible source may not be sufficient to tease out the complexities of what we have to face in discerning how to best exegete "Gehennna" --- or Hades or Tartartus for that matter. It's not just a lexical issue alone, and I don't think the book of Enoch (or the collection of writings it comprises) gets to be the definer in this discussion.
Then too, you and I know that different Jewish sects had different views even back in the 1st centuries (both B.C. and A.D.), making it hard to say, "The Ancient Jews precisely thought X about the meaning of Gehenna."
Now, please keep in mind that in my saying this, I'm not trying to debase any respect that the rest of us might be inclined to favor you with. For my part, I appreciate very much your firmness of faith and that you've been on this site for as long as you have. I also appreciate the fact that you served in the armed forces for our defense. But I just don't think these details, as much as they are respectable, are definitive in our common endeaver to understand whatever fear of Hell we could or should have....or maybe shouldn't have.