Wow, NICE job!!!!!!!! Lot's of fine thought and work went into that. What brand?
Being that we occasionally get down into single digits I can empathize with your dreams and considerations. Took me 5 years but we're now enjoying and giving away the best Zill mangos (just grafted 7 new ones which took), avocados, pineapples, cherimoya, rollinia, citrus, maters. You're gonna have some fun!!!!!!!!!!
All my trees are in bottomless RootBuilder pots which I see you use.
Mark