Thanks Alan for your post.
Since my initial question about flap/elevator mix, I've flown this ship 15 times. Initial flight was, as per the manual, with a CG 25 mm forward of the spar. I found it quite nose heavy, and shifted the CG back to 12mm forward of the spar. This was perfect. I had also set in about 1/8 inch of down elevator mix with full flaps, and actually had to change that to a trace of up elevator mix. Now flight characteristics are stable and excellent.

One interesting thing I've noted is that with flaps down at 35 mm for take off (as per the manual), the nose wheel was hard to rotate, and actually seemed to be "wheelbarrowing" on the runway. I changed to taking off with no flaps, and that stopped that problem. I may try taking off with 20mm of flap now, because it takes a fairly long take off roll to get off.

An additional issue was that the upper fuselage was heating up severely during taxiing in. I have a Jetcat P-80 SE with stock pipe, 3/4" between end of engine tail cone and front of pipe bellmouth. I cut the cheater holes in the bottom fuselage, between the strakes, as suggested by prior posts, and they helped only slightly. Then I mounted a 0.016" thick aluminum plate covering 1/2 the diameter of the inside of the upper fuselage as a heat shield, and that cured the problem.

All and all, an excellent flying ship that I am completely delighted with.