Mashing higher won't really give you more sweetness, just more body. At 49 IBU you won't have to worry about it being too sweet. Higher IBU's to make it 'American' will also hide some of the lactose sweetness.Making the coffee is different. I'd think you'd get a coffee pot on the Warner plate flavor from that.
I would also might mash higher.
My thought on masing that low is that I will already have a ton of sweetness from the lactose.
But all that is just options - I'm sure the recipe will make tasty beer as is.
+1 on the mashing higher leading to more body rather than sweetness. Even though you'll end up with a higher FG, what is left behind is unfermentable dextrins (which aren't sweet) as opposed to sugar.
And if you really wanted to go "American" on the hops, then an ounce or two of Centennial at flameout would be the 'merican thing to do.