I had done a lot of research, including on this site. I won't recap that, but offer my first-hand data and some pics here. Method Standard (black) wheels, 17". I already had the aluminum wheels from factory, which in hindsight was a total waste of $850.
I thought originally I would be happy with the factory aluminum and 265/75r16 (accepting that these were wider than 'recommended' width for the 6.5" wheels). The more I thought about it though, the more I was leaning towards the 285/70r17's, so I bit the bullet and went with the larger wheels so I could support larger than 265's if I wanted to, and didn't mind the extra width even for the 265's - and they don't look bad at all. So, ordered the wheels through Discount Tires, and they test fit the 285's on there. They fit, so I didn't even try the 265's and am very glad I went with the larger wheels.
Regarding the 285's: Back is totally fine. Just to take that off the table. There will not be any rubbing there, even at full compression, or compression on hills or turns. There is no rubbing at all on the fronts so far. I have not been off road yet. As you will see in the pics, there is not much clearance left, and I fully anticipate some rubbing against plastic mud flaps and possible plastic work towards front of the wheel well. Nothing I am not prepared to cut into though, and, maybe there will not be rubbing. There really is not that much articulation in the Sprinter suspension. I will post updates if/when they occur on this front. The take-away here is that 285's on the Method Standard fit fine regarding clearance of shocks, brakes, and everything else including turn-to-turn when parked or driving on flat pavement. Jury still out if there will be some rubbing under more stressed conditions, but it does not look like it will be bad.
Pics coming in next post.