I have a couple cases of Camco paper that is 4 1/2" tall and firm, but it has been discontinued and is now sold as a 4" paper, this was two years ago, don't know if you may be able to find a RV shop that has old stock, maybe? A310 uses Kirkland, it's the right height, it's a softer roll, but it compresses and looks like it will work not to bad, I have only dry fitted Kirkland, we use it around the house. The Frantz elements are 4 1/2" tall, the diameter may be a tenth of an inch smaller but it should still seal around the outside, I am unsure if you will be able to compress the Frantz paper, something I always thought of trying if I wanted a super firm 4 1/2" paper.