Harvey …… I enjoyed your original post and discussion so much; I had to give it try.
The tree pots, where found on eBay at a reasonable price ….. here. I tried ProMix HP and Sunshine #4 in various trials and to each added more perlite. Maybe too much! No greenhouse, so I cut 1.5 liter “FIJI” water bottles in half to help with humidity. They fit snuggly and some I cut vent holes in top but, then abandon in an attempt to keep gnats at bay. Also, had pots on heat pad with tray between, approx. 75 deg. in mix!
All in all, think my success rate in rooting is about 50%. Keeping uniform moisture content seemed to be problematic. The FIJI top hats didn’t work out as envisioned. Also the fact that we had very low humidity this spring, like a week under 10%, hasn’t helped. And, then there are those gnats….urgh. They have been like the plague this year, even finding a way between the tight fit of FIJI bottle on tree pot.
I will try again, only next time ditch the FIJI bottle tops and put the whole tree pot in a large plastic storage box, as I’ve done with Jon’s Uline bag method. Which, I also tried for the first time this year, with terrific success. For me, the all-important humidity issue is much easier to control via Jon’s method.
Thanks for all your follow up posts.

Jon's Uline bag method