I have no ideas to add regarding your settings and charts, Dave. You are in good hands getting far better recommendations than I could make. I believe you are an engineer so will give extra details to enable your go or no-go decision early (and I'll have this post to inflict again on others
who do come along with the leak problem we have shared.
)
But I can offer an idea and method to stop your lip leaks. (With as wide a collar as you can find and
then adapt to (after several days), I claim there is no need for a chin strap which may aggravate upper airway obstruction anyway.) Warning: your eyes will glaze over and you will go to sleep reading this.
I was once an envious person who "could never use a P-10": a mouth breather in sleep with leaky lips to boot. But always awakened by various FFMs' leaks, I got to the point of doing whatever it would take to stop mouth breathing (and supine sleep) so I could use the highly praised P-10 with its minimal perimeter to be sealed.
The link to my image below shows two solutions that have worked almost totally without failure for more than about three years. Not shown is my cervical collar. For two years I wore the vest along with my first 3 1/2 in. collar, but found, after about 2 years, that I could go without the vest with a 4 in. collar (as now for several months).
In the pictures, ignore the vest and boxes, as were put inside its pocket, and ignore the chin strap, which was the best and last one I improvised or bought, but cast aside 4? years ago. I do still use the anti-asphyxiation device, largely because its 90 degree turn makes hose management easier, hose draped off my headboard as it is.
Most of all, I recommend the
non-prescription Silipos Gel-E-Roll seal you see. It is a mineral backed fabric (from a 4 in X 48 roll) which is elastic length wise. That is my lip seal. It clings, even with occasional drools, but it does-not/will-not adhere like tapes. The first couple seconds against the face it feels like a clammy dead fish. I wash it gently with soap, not often enough, probably, and one seal lasts 6 months or more.
You must have a retainer to hold the seal in position on the face with traction and to press hard enough to keep the seal against lip leak pressure. You need some way to apply a normal or radial force inward toward, say, your uvula.
My first improvised seal retainer is pictured beside the ruler. It is the top few inches of an old elastic compression stocking. It has double thickness elastic fabric where most needed at the top of the retainer (and stocking), about 3/4 in wide. With the top edge of the seal matched to the top edge of the double layer elastic the pair work fine with a P-10 when the upper edge is placed within 1/8 to 1/4 inch below nostril openings, even a bit lower. The velcro straps are attached to the ends of the retainer, overlapping it a bit there, the hook end being quite short.
My pose (without my then-usual c-collar) is with the later professionally sewn successor of my DIY retainer and a smaller piece of Gel-E-Roll (2 in x 6 in).
Think of the sealer and retainer pair being similar to the old inner tube and tire pair: the tube for sealing, the tire for tube shape and size restraint against pressure--forgetting about all durability issues.
Moments ago, I folded a 20+/- in. square bandana on the diagonal and folded that triangle's long edge down again to have four layers of cloth (for about 3 inches) to cover and compress my upper lip and more before tying it in back. My bet is that bandana would work as a retainer in a pinch and could be improved with some velcro, elastic from a fabric store, scissors and a good stapler.
One learns techniques for donning all easily. With seal lying as shown on retainer (lower right pic), with two hands grab and pinch together seal and stocking at upper right and left left corners of seal. Stretch it a bit (preloading it) and press it in position against upper lip. Slip fingers around the top edge without losing its preloaded tension, to make the velcro strap connection at side or back (however you designed that). After fastening, with the elastic seal and an elastic retainer one can carefully move them a bit for best alignment and most comfort. With a bandana, it would take more fiddling to get tension right, particularly, to keep from losing tension during placement and when raising or lowering chin after fastening.
Two caveats:
---My 95% IPAP is just below 14 cmH2O and I believe the method would withstand much more pressure with more tension in top edge and strap connection of retainer.
---Chin shape or its relative position to neck fleshiness and size may not allow the method.
One other advantage: Radial inward force is applied to the skull and upper teeth roots, not to a hinged jaw which has anterior-posterior play and can recede a bit causing airflow problems for some persons.
Links:
---My attachment I've posted a few times
attachment.php (889×577) (apneaboard.com)
---My Gel-E-Roll source with the most reasonable price and related
non-prescription gel products (4 in. squares and circles)
Gel Solutions: Solve Prosthetic Fitting Issues with Gel | Amputee Store . I need a roll of Gel-E-Roll from them, again, but will also try their 4 in x 4 in gel pieces as a substitute after noticing them a moment ago.
Whether you try this approach or not, I wish you good luck, Dave, and improved sleep and therapy.
I have no particular qualifications or expertise with respect to the apnea/cpap/sleep related content of my posts beyond my own user experiences and what I've learned from others on this site. Each of us bears the burden of evaluating the validity and applicability of what we read here before acting on it. 
