Fitz - once again appreciate you passing on very helpful threads full of all kinds of information. I have read through the first six pages of posts and thought I would respond. Excuse me if some of this is covered further on down in the thread. I remember I came across the side molding leaks on the Transit Forum here (I can not remember which thread it was but it was one of the Sprinter vs Transit threads) by the way it was noted that Transits have the same problem:
Ford Transit Versus The Competition - Ford Transit USA Forum
I also found this detailed explanation of the side panel leaks with images, and how to repair it. Note it was pointed out you want to do this first thing before you begin the build out of your van.
This was just posted three months ago so this appears to still be an issue with current models. As the author notes this 2014 Sprinter calls Palm Springs home, in the California desert - "during a drought", about as dry a climate as you can get.
Regarding State Farm - “we don’t care if you take the vehicle off-road, we will come and get you wherever you are” emergency road service plan. I have State Farm too so I am glad to hear about this. I will say though I recently had a minor claim with them on my high mileage sedan and some adjusters were trying to get away with using "recycled parts" as in junk yard parts that meet State Farm's "standards". Even in California where the law states you have the right to take your vehicle to whichever body shop you want (the best body shops do not use used or third party parts unless there is no other alternative), State Farm can get around that by forcing you to pay for the difference between recycled or non OEM parts and the real factory replacement parts. I called the State of California Department of Insurance and they said the insurance companies can get away with it BUT there are some limits to this loophole. The part can not compromise the safety of the vehicle so with many parts you are on solid ground if you put up a fuss and demand factory/manufacturer parts. Insurance companies know this so they do cover the cost of new factory parts that clearly fall into this category, but this insurance industry lobbying loophole allows them to get away with trying to undercut the law in my view. Pay attention to your claim, get a detailed invoice with part numbers, and check it. Call up the Department and talk to them, as I spoke to someone who was helpful in explaining the nuances of the law and how to make a case for new factory parts in your repair. I think State Farm and many other insurance companies only cover the cost of original factory parts for the first three years of the vehicle. AAA of California is the only company I have found so far that offers an additional option to your standard premium that will cover new factory parts for the first ten years (it may be 15 years - depends who you talk to at AAA). The additional coverage works out to approx. $50/year for a $45K vehicle.