I started the lower roof with 9'-6" and with the 2:12 slope, got highest point of lower roof at 15'-4". I took the highest point of the lower roof and added 30" for the clerestory and 1'-6" for the roof thickness and I set that as my lowest portion of my higher roof at 18'-10".
I also added gutter at the south side of the east and west wall, is that necessary or I just need it at the lowest point of the roof? For me, it made sense to have it there as well to catch the water falling off the roof.
Let me know if you see anything wrong with this. Testing next week!