I don't trust dealers for WDH setup but I do trust a tape measure and scales.
I really can't offer valid advice for your setup because it may well very different than my hitch setup.
When I setup my Reese DC the top of hitch ball was 1" higher than top of trailer coupler, level.
Dropped trailer on hitch whiched dropped rear 2" and raised front 1".
Adjusted trunnion bars where rear of truck came up 1" and front of truck went back down 1/2" and trailer is only 1" nose down when all was said and done.
So 2 things jump out with what you describe in post.
(1) Hitch ball 3 1/2" below trailer coupler while both sit level unhook, hmmmmm.
(2) 3 1/2" of nose down is more than I would want.
Hope Anderson responds with the answers your looking for.