My experience and recommendation would be to go with a 15x8 alloy
wheel with 3.75"-4" backspacing.
I have had, and sold, two different sets of 15x8 steel wheels, and a set of TJ Rubicon Moab wheels.
Loved the Moab wheels, but it was hard to find a load range C in a 16" size. They also needed wheel spacers when I wanted to go with a bigger tire. I didn't want to buy spacers.
The steel wheels would often lose their balance after offroading aired down. Probably bent a little? IDK.
I have seen many 10" wide wheels loose a bead on fellow club members rigs while aired down. I have yet to pop a bead....knock on wood.
With the 3.73"-4" backspacing, I think the wheels stick out far enough and look pretty good. My tires are not "tucked under" my Jeep. I don't think the mechanic you talked to doesn't know to much about backspacing. It's the backspacing that will push your tires in or out. Most stock wheels have 5"+ or so.
15x8 steel wheels, 3.75"bs, with 33x12.5x15 tires
15x8 alloy wheels, 4"bs, 35x12.5x15