Anyone have the PinTop system with 37’s? If so did you have to trim for them? I’m looking at 17x9 +18mm offset rims with 37’s if I don’t have to trim. Worse case I settle for the same set up with 35’s.
I wouldn't be afraid of a little trimming. You're going to spend multiple thousands on wheels, tires, and suspension setup to make it ride better than stock, trimming a little of the wheel liner, or at absolute worst a hair off the pinch weld, is really non-issue. Don't be afraid of it, you're not going to ruin your truck by cutting a 1/4" of pinch weld.
The wheel offset you're looking at should be good to go. There is a range and +18 is within it, maybe even the most ideal. Keep in mind that all 37" tires are not created equal. All will have slightly different true heights, and side lugs. A Falken AT3W in 37x12.5 will probably clear no problem, a Toyo MT in 37x13.5 probably won't clear as well. Partially due to tread design, partially width and sidewall lug, partially due to actual height.