If you don't have a squat rack then learn to love the deadlift. It's a great exercise. When I was starting out I felt like you did watching that guy curl. It was so much fun to load what seemed like heaps of weight onto a bar and pull it from the floor, knowing that it would do me good and that - unlike the curlers - I was getting stronger every time. It doesn't get more basic and more manly than just lifting heavy **** up.
No wonder your core was hurting after doing deadlifts with a free bar for the first time.