Preheat the oven to 375°F (190°C).
Cut pork tenderloin lengthwise, open up, pound out to an even thickness.
Mix reserved pineapple juice, brown sugar, chili powder, and garlic powder; brush over pork.
Add pineapple and red pepper, wrap the meat around the pineapple, secure with toothpicks.
Wrap bacon slices around the pork to form a log.
Roast for 25-30 minutes until internal temperature reaches 155°F (68°C) and bacon is browned.
Allow to rest before slicing.