Combine marinade ingredients - soy sauce, grated onion, garlic, apple cider vinegar, black pepper, seasoned salt, sugar - in a bowl and stir together well
Wrap bacon around both pork loins and secure with toothpicks
Place bacon wrapped pork loins in a 9x13 baking dish and pour marinade over, turning pork loin to coat - cover and allow to marinate in refridgerator for up to 3 hours - it can get really strong so marinate at least a half hour but no longer than 3 hours - turning pork roast a few times.
Bake in a 300° oven for 1½-2 hours - turn roast once and baste a couple of times. Internal tempreture should measure at least 145° to be cooked fully
Allow to rest for 3-5 minutes, slice thin to serve