Some random shower thoughts, having just returned myself from doing lung clearance, something I've been doing a lot since we cleaned up the mold issue we had:

If you think doing lung clearance might cause actual vomiting as well, don't do it in the shower.

Instead: Get naked, stand over your toilet and cough into the toilet. Then shower before getting dressed again.

Don't skip showering. Store your clothes away from where you will be coughing/puking so they don't get blow back.

Don't assume once a day is sufficient. Doing lung clearance multiple times a day is not unreasonable during a life-threatening health crisis.

If you can't bring it up, drink something and eat something salty. This will help you cough it up.

If you roll over and it provoked a coughing fit, you probably have fluid sloshing around in your lungs. It's a good idea to attempt lung clearance at that time.

It's more or less free (though it could drive your water bill up). It just takes a few minutes. The only known side effect is breathing easier.

Okay, okay. I sometimes get dry skin from showering 500 million times. It's less annoying than not being able to breathe.

Try to not fall in the shower though. Getting bruised up would not be a good thing.