Hi Hi,
The answer to your question really depends on your specific stoma. You're right that using the ring will make everything thicker, but if your stoma shoots straight out that won't be a problem. If your stoma shoots off-center or to the side, it probably will. What you need to do is measure the thickness of your barrier and ring before you put it on. Then when you take it off (in however many days you get out of your setup), measure it again. That will tell you how much the combination has grown in thickness as it swells during use. What you'll find is that the barrier swells more than the ring, which might lead you to believe you can get away with no ring if the combination swells to a height that is higher than your stoma. But you need to know the ring swells faster than the barrier. That's important if you don't cut your barrier hole small enough to be really snug against your stoma, which you really shouldn't do. If you leave even the smallest gap around your stoma and use the ring to be snug up against your stoma, you're instantly protected from liquid output, as the ring swells very fast. If you now leave out the ring and there's any gap between the hole in your barrier and your stoma, output can get in there before the barrier has had time to swell and you'll develop a leak. What I do, because my barrier swells a lot, is I use a rolling pin and flatten my ring until it's really thin. I cut it so I can then wrap it tightly around my stoma and then put the barrier on. Note that Hollister makes two size rings: a thin 4" ring and a thick 2 1/2" ring. I'm using the 2 1/2" ones now, which I flatten, but have some of the thin 4" rings on order.
So, depending on the direction your stoma shoots and how much your barrier and ring swell, you should be able to figure out what combination of ring, flattened ring, barrier, or only barrier is what you need. You dig?
;O)