Preheat oven to 275 degrees. In a 1 quart measuring cup, pour approximately 2/3 of the jar of BBQ sauce. Add bourbon a little at a time, using a whisk to thin the sauce with the bourbon. Use your judgment as to how thin or thick you want the sauce to be. The quantities here are very forgiving. Keep adding a little sauce or bourbon until you like it. Whisk the two until completely blended.Using heavy duty foil, or two layers of regular foil, lay the tenderloin pieces on top of the foil, then pull up the sides of the foil to make a “boat.” Pour the BBQ sauce mixture over each tenderloin, dividing sauce evenly.
Seal the foil packets so that the meat has room to breath. Bake for 3 hours.
Remove tenderloins from oven. At this point, the meat is ready to deliver. Just wrap in newspaper to keep warm enroute. To serve the meat, open packets, pour off liquid into liquid measuring cup or creamer. Pork should pull apart or slice easily. Serve with reserved sauce.