That is a good question Tom. Most masks are rated for up to 20cm. I have had DECENT luck with nasal masks at these pressures. I have found that as the soft rubber on the nasal pillows degrade the problems get worse. In my experience I believe nostral flairing might be the bigger problem at these high pressures. Bpap may eliminate this as it lowers your average pressure.
You may see if you can get a loner or trade in. I hope this helps.