So the "use a truck from the dealer lot" is kinda **** move. Not in reference for the dealer but the potential buyer of that vehicle. Unless its a used truck no one is going to remotely think to pull up a carfax on a new vehicle because it has never been owned. A new owner could get slammed with a bunch of hits on a new truck with them never even have purchased any parts for at all.
There's a couple of ways to dodge the VIN logging.
1) Search for the parts you need with your VIN BUT do not order with it. Just get the part number you need and than back out. Go back into the system with your normal information, pull the part number and do not provide your VIN. Some Ford OEM parts sites do require VIN regardless to order so just be aware of that.
2) IF the site you found requires the VIN, take the part number you found using your VIN from the Ford OEM parts site and order it from a 3rd party. Something like rock auto or whatever. As long as you have the correct part number associated with your VIN the other places could care less/don't even ask for a VIN.
3) If you die hard want to order from a Ford dealer/OEM parts site and they require a VIN you're pretty SOL at that point. You can do the kinda **** move and snap a photo of a dealer VIN. The less ******* move would be if you have like a Copart account. Search for Raptors on there (a lot are totaled) and pull a VIN from there. Also some times they even take pictures of the door jam with the VIN so you wouldn't even need a Copart account. Most of those trucks are never going to have a clean title so a carfax report is really moot at that point.