My preference is a nasal pillows mask but traditionally, I am a mouth breather. I have tried a chin strap and mouth taping. However, what has worked best for me is to consciously throughout the day to place my tongue in the roof of my mouth to create a habit of keeping my mouth closed. Over a short period of time creating that habit has helped me keep my mouth shut and ended the dry mouth most nights. I now find myself unconsciously and routinely resting my tongue day and night in the roof of my mouth. Just the awareness of realizing that when my tongue was at rest in the roof of my mouth, my mouth is automatically closed and I am breathing through my nose helped me begin creating that new habit.
I have a friend who had a reaction using a SoClean machine. It would be interesting to go back to your previous way of cleaning your machine and see if the issues you are having cease.
I use a 100% silk scarf to wrap around my strap to protect the friction on my hair. I notice when I don't do this that my hair shows my scalp where the strap has rubbed.
Do you know if you will be using a CPAP or an APAP? I was diagnosed decades ago and have struggled for years attempting to adhere to the PAP therapy. It was only recently since setting my machine on the automatic setting that I noticed a huge change. My scores before changing to the automatic setting were almost non-existent and now they range from 80-90 most nights. I do notice that the higher my nightly scores are the better I feel.
I think that many providers are not giving enough credit to machines that run on automatic. When I changed my CPAP settings to APAP, my life changed. I had good intentions every night going to sleep with my CPAP only to find it elsewhere in the AM. Since switching all the settings to Automatic, I actually wake with my mask still on most nights. My non-existent scores of the past because I didn't leave it on long enough to register now are ranging in the 80 to 90 range. A friend told me in some countries that APAP machines are actually sold at the local drug store as the settings will adjust to your needs.
I struggled for decades with various masks. I would begin the night with good intentions only to find my mask on the floor or elsewhere in the bed when I woke. My bed also looked like a warzone. My CPAP was on a pre-set setting. A friend told me to try setting the machine to automatic on all possible settings. This has changed my world. My sleep scores which really never existed before have just to great scores of 80-90 most nights. I think I was unconsciously doing exactly what you describe because of the set number. The automatic settings adjust to my needs throughout the night.
There is a product called "Pad-A-Cheek" that has worked great for me. I am in the cosmetics industry so that has been a large issue for me. https://www.padacheek.com/
Additionally, if you or anyone has concerns about their straps causing friction on their hair, you can use a 100% silk scarf to wrap around the straps of the mask to protect your hair.
I would encourage you to check out the following PDF located @ https://swhr.org/wp-content/uploads/2017/11/SWHR_Women-Sleep-Apnea.pdf
to see if anything resonates with you. Sometimes, you could be experiencing symptoms that you are unaware are symptoms. Then sometimes, there are no symptoms. It would require a sleep study to diagnose. While this seems like a huge inconvenience right now and unfair, it could be a blessing in disguise if you can avoid some of the long term issues that come as a result of undiagnosed sleep apnea.
Are you using it on auto mode? I just made that switch and the difference has been amazing.
I am familiar with Meniere's disease but not Benign Paroxysmal Positional Vertigo. Do you think that you could have sleep apnea? Are you tired during the day? Do you fall asleep while just sitting reading or or watching TV? If so, you may want to ask your GP to refer you to a Sleep Provider for a Sleep Study.