I have previously posted an earlier version of my questions and ideas with the background of my situation (Roof Retrofit, https://www.greenbuildingadvisor.com/question/roof-renovation-options), and I am updating my questions and ideas hoping for additional consideration and insight.  Since the previous post I have not been able to get a contractor willing to do the renovation work, and am trying to develop a plan that I can get done.  There is resistance to replacing the sheathing due to concern about the effort required to remove the old sheathing and exposing the open truss attic full of cellulose.  The wind is always blowing.  Spray foam for the cathedral ceiling is also very expensive to get to R48+.  My new idea that I am asking about would be to remove the sheathing over the cathedral ceiling and flash the open structure with spray foam for air ceiling, and then completely fill it with mineral wool batts.  After re-sheathing with 7/16 OSB or plywood to act as a baffle, add 2×3 or 2×4’s along the top of the rafters to strengthen them and act as spacers for a vent channel, topping the spacers with 5/8 or 3/4 sheathing.  My understanding is that the 7/16 panels would be suitable as a vent baffle, especially in a dry climate.  This same approach would be added over the existing sheathing over the attic end of the house.  This would presumably allow adding cellulose up to the underside of the current sheathing at the outer edges to increase the cellulose depth where the truss depth is shallow and the current venting severely restricts the cellulose depth.  All of this to be well fastened to current code, and hopefully strengthen the roof structure in view of the increased snow load requirement.  This would avoid removing much of the existing sheathing and dealing with the wind over the existing cellulose.  Also it would allow full depth mineral wool in the cathedral ceiling rafters.  The only down side I am aware of is the increased weight of the additional sheathing, but the rafters and the top chord of the trusses would be strengthened.  Does this sound like a reasonable idea?