Great job sharing your strategies Ash and good luck with the journey.
As a counterpoint to your path, I'm doing something slightly different
I'm upgrading my AQ ONLY and leaving my BK at 10 because...well he's kind of useless. The AQ on the other hand has been responsible for literally leveling bases all on her own on more than one occasion. My reasoning behind focusing on her is that once she's sufficiently leveled - she can actually speed up the collection of DE.
I just finished 3 boost sessions today ( 6 hours total ) to go from 25kde to 100k de using nothing but giants, barbarians, and archers (1,1 and 2 rax respective), 3 rages 1 heal, and both heroes. That started her UG to level 20. I'll most likely take her to 25, then pause to let the BK catch up to at least 15, but I'd rather have a fully upgraded hero (full-ish anyway) rather than 2 half way upgraded heroes.
I farm the DE, but then I gem the build time...For 7 days it's 1000 gems, so what I do is, I attack early in clan wars, then immediately put her to sleep. We have a sufficient gap between clan wars that I can get 5 out of that 7 day schedule dropping the overall gem cost to maybe 200-300 gems per level.
I hunt primarily in low c2 (crystal 2 league but around 2100-2200 trophies). That gives you the crystal 2 bonus (200de), but you fight crystal 3 bases (high th8s, mid th9s). Maintaing trophy count with TH9 GBarch is totally doable. The giants I use combined with a single rage to punch through outer walls and dive straight into the core of the base. If you plant the 11 you have on a single wall, you can punch through without having to use wallbreakers.
1 day into this season with those 3 boost sessions, I'm at about 70 attacks, and now I can relax for the rest of the week, or just continue to farm up my walls
Good luck on your journey!!!