OEM 5th wheel

[crazydog]

Not sure if this is the best place for this question, but. . . . .Previously, I towed a gooseneck horse trailer with these trucks and an after market hitch.  My 2019 has the OEM set up with the converter kit?  Anyway, hooked my trailer just now and I have noticed:

 

there's less clearance (obvious, I guess, since the old hitch would have been a few inches above the bed).  I have 7.5 inches.  I've read that 6 is minimum.  Since I've always had more, I'm just a bit nervous to go with 7.5.  Would you guys recommend adjusting the gooseneck??  I think it will go one more hole, giving me a couple more inches, likely.

 

The instructions say the safety chain hooks go behind the ball.  However, in my old set up, the chains were in front.  Behind . .the chains don't even reach.  I have moved them to the front but .. .just wondering why it says to go behind---is this a problem?

 

Also--sidenote---has anyone had issues with a "musical"- wind-blowing-through-your-grill kind of sound?  Mine was doing this for months before I got it in to have the grill adjusted--there was a flap or something, that wasn't right.  Anyway, it died down, but I swear the noise is back again   WTH?