I removed ceramic tile from a sunroom and want to replace it w/ engineered flooring. I don't want to have to grind off the thinset morter left from the tile. I was thinking about either 1. Laying down a 1/4 felt to take up the uneveness and then put down a 1/4" plywood subfloor or 2. Level the floor with leveling compound and then putting down the plywood. If I go with option #2, would I have to float the finished floor?