Bringing this back to life a bit. I have abandoned the 16" wheel idea, for now at least, and I'm going 17" for winters.
Last night I picked up a set of 2000-2006 BMW X5 wheels.
They are 17x7.5 5x120 with an offset of +40mm, so that's pretty close to stock MDX specs (just 7mm more outboard).
Also, the hub bore is 64.1mm for the second gen MDX and 72.56mm for the BMW X5 wheels, so I've got my hub rings on order (4 Hub Centric Rings 72.6mm to 64.1mm | Hubcentric Ring 72.56 - 64 fits Acura | eBay
Next up is lug seat. BMW uses a cone seat, Acura uses a ball seat, so I have to buy a new set of lug nuts M14x1.5 with 60° cone taper. I'll order some new lug nuts this weekend, I just need to measure the height I need before I order.
The last thing that may throw a wrench in the works as i get these fitted is the bolt hole size. BMW X5s through 2006 used M12 lug bolts (possibly, haven't fully confirmed), the MDX has M14, so there is a chance I may have to enlarge the holes on the wheels to get my wheel studs to slip in, but I should be able to find that out pretty quickly. I've seen conflicting info in my research on whether or not the first gen X5 used M14 or M12 lug bolts, so they might be the proper size holes already.
One thing to note, a lot of BMW wheels come in a staggered (different offsets for front and rear) configuration, this wheelset is not staggered.