My second floor is decked using 2 x 6 tongue and groove boards layed at a diagonal across the floor joists. Before I layed carpet I went around and screwed down the squeeky spots. Soon after the carpet was layed the squeeks came back. My plan is to take the carpet up, screw down the boards again then put in a self leveling underlayment to fill in all the gaps. Then add a layer of 5/8 tongue and groove plywood. I was going to use constrution adhesive and screws. Once that is down I plan to put down a hardwood floor. Does this sound reasonable?