Honestly...15p Enertia and be done.
I had a similar dealer experience to Goldnrod with our prop when we got our new boat in 2017. The collective advice in this forum was spot on, the dealer was off by one pitch. They dug their heals in, but finally relented and let me give it a try. Their tech acted shocked at the difference it made.
With you keeping your boat up on a lift, your toons are going to stay nice and clean, and consequently the boat will run fast. Go with the 15p Enertia as so much of the advice above. It works out both numbers wise, but also experientially. If you stick with the 14p, don’t run it over the 5800 rpm. I would never exceed that, especially after the Mercury rep says not to.
Congrats on the new boat. Looks great in your pictures. Exciting times ahead.