I am replacing a toilet for a 5-inch ID (yes, I measured it) toilet flange that is connected to a 4-inch pipe. The depth from the flange surface to the top of the pipe is 2-3/8 inches. I've read about using silicone for the Dutchman fix, but ABS is only 4.5 inch OD - how do I seal the annular gap? This seems too large for silicone. Would a layer of 1/4-inch rubber sheeting (sealed to the ABS OD) work?