Ahh, the warranty debate is back.
I fully understand a person not wanting to make a gamble of this nature. However, if you modify any part on the car (let's say computer tuning) and the wiper motor fails, the tune had/has zero connection to the wiper motor and is not at fault for it. If the tune isn't at fault, they then have to replace/repair it.
Yes, Ford will obviously have deeper pockets and a wider attorney staff, so it's still a gamble.
On the lighter side, I'll use my experience for example.
I've done massive amounts of both new and used car purchases from my local dealer, along with tons of service work. Saying my dealership and I have a good relationship, is a vast understatement.
I ordered all my goodies from Livernois and while having an off topic conversation with the service manager, he asked what I intended to do to my 2016 because my 2011 was in the shop after I had work done.
Anyways, he offered to me that if I had his lead tech install the parts I mentioned, he would honor my warranty unless I added an external fuel source (methanol/n2o) and caused a catastrophic failure.
That thread is on here somewhere, but I don't feel like finding the link.
To any means, it's worth being upfront with the service guys and possibly building a relationship with them.
Being without a tune on these cars, is a serious kick in the dick.