Struggling with sinus pain

I've been using a CPAP for about 5 years now, mostly with success. I have a ResMed S9 CPAP with humidifier and a Philips Amara View mask. I quite like this mask even though I get some leakage as I toss around at night.

I would use a nasal mask, but my sinuses are extremely sensitive. Even with the full face mask, and with the humidifier, air entering my nose will usually cause significant sinus pain. My sinuses usually aren't blocked- I just have pain that will generally subside in the morning, occasionally needing advil. I also frequently have a very dry mouth. All of this is better than not breathing at night, so I deal with it. The one time I tried a nasal mask, the pain was extreme. I guess I am a mouth breather, though not 100%. It comes and goes. During allergy season when I'm taking zyrtec to stay alive and my sinuses are raw, I will mouth breathe more. Other times of year I'll often breathe through my nose.

I'd be tempted to try a nasal mask if I could make it work. Does anyone have experience or advice in this area?

I use an Amara View as well and develop a lot of dry mouth when I breathe through my mouth. Perhaps dry sinuses are the result of dry mouth. I use a boil and bite mouth guard to keep my jaw from going slack and this is when the mask ends up slipping into my mouth resulting in huge leaks.