Firstly, this is awesome.
I don’t know how you’d induce sneezes by tickling (tissue up the inside?) but whatever you do, I want you to try it once you’re right on the edge of cumming, so you have to fight both urges. If you sneeze, you have to stop playing, for two hours – there’s an incentive.
You can also induce sneezing by looking at a very bright light, so that might be fun to try.
I also know putting a vibe on your nose can make you want to sneeze (the best way to test how strong a vibe is in a store, before you ask why I’m into nose play). So explore moving from clit to nose and back keeping both ‘edges’ going.
Another twist might be to have to deny five sneezes before you can have one edge, or vice versa.
Finally, at some point, please try sneezing as you cum, I really want to hear about that!