I am in the process of remodeling two bathrooms. I'm planning to replace the tile flooring with vinyl. For one of the toilets, I can easily replace the flange by cutting the pipe from the floor below. The second toilet is not so easy. I don't have easy access to the waste pipe from underneath because it is directly above a heating duct. It also looks like the flange is connected directly to an elbow. The drain pipe is 3" inside diameter. I understand it is preferred to have the flange resting directly on top of the floor, but it would require either taking a heat duct apart or pulling up the subfloor. So my question is if I tear out the floor and put down new underlayment and vinyl, I'll have a 1/8" gap between the flange and floor. Is this acceptable, or will I need to shim the flange and toilet? And if I shim the flange will the toilet need to be shimmed as well or would it still be possible to push it down tight to the floor?