I use barrier strips under my wafer all the time. It's expensive though.
What I do is clean area with antibacterial dish soap and then rub in some conditioner which I then wash off with regular soap. The anti bacterial soap kills any infection on burned skin that will continuously weep. If no burns then I just use moisturizing soap like Dove.
Next after drying well I apply an extremely tiny amount of stoma adhesive around stoma and dry brush off until it disappears..else it will come off later. Then two coats of generic Flonaze (the nose stuff) dried well after each coat. This stops the stinging.
I use olive oil based lotion on my scar tissue and belly button (reduces itching) covered by thin cardboard (protects scar from adhesive). I usually have this prepped as well as the wafer hole.
Then I apply a ring of no sting paste around stoma just enough to cover the skin about 1/2" around stoma, it's not meant to glue to wafer, rather to protect the skin.
I apply 50/50 cut moon shaped barrier strips on top of the paste next to stoma and pressing down. If the skin was very sufficiently blow dried, it should stick well. This also holds the cardboard over scar tissue in place. The object of this method is to ensure a solid seal around the stoma. Not just quick slapping a wafer on.
Next I apply two rings of paste around stoma just a little bit away and press convex into it with just the edges of the flange touching the skin. Not pressing down too much as I don't want to squeeze out paste or cover the wafer hole, rather create a wall of paste. I should say I do this laying down.
I then put external barrier strips all around to hold everything in place and heat activate with blow dryer. Then wait a few hours for the thick paste to set up. No belt because it aggravates my graneoluma.
Now this creates a very strong and stiff bond that as long as I don't bend at the stomach and only via the waist then it's fine.
It lasts anywhere from 3-7 days, with a 9 day once. The barrier strips under the wafer combined with the exterior ones create a pocket in case a leak occurs where the paste meets the barrier strips.
However bending over via stomach can cause the paste to tear the skin and cause a leak around the stoma.
I rinse the one piece convex from the bottom using either antibacterial dish soap and water (kills the bacteria causing the odor) or predissolved antacids in water (like on the road). Leaving some dish soap water or antacid water in the bag after a flush assists killing future digestive enzymes (bacteria) as it exits the stoma and kills the odor.
For gas and stoma farts I haven't found a remedy because the digestive enzymes produce gas a by product of the digestive process. However certain foods and drink can assist with gas or reduce it.