I'm doing the same thing. Just 8 endo-flames on a 40/#endoflames timer if memory serves. I dump a ton of coal into the dropper and by the time I get back I have a full mana pool.Mana is essentially free once you achieve the ability to run an Ender Quarry with top tier Speed Upgrade 24/7/365
I have almost 1 million coal and another 100K Coal Blocks. I haven't make 1000 Endoflames to use it all, but I certainly could do so. I only have 4 Endoflames actually. But it's trivial to automate an OpenCrate/Hopper and just keep making mana around the clock. I could spam my little 4-flower setup 500 times if I wanted to. The problem is how to STORE all the mana... Mana Tablets are not a good answer. Right now, I am using up all the mana each morning when I log on, making Terrasteel with it.
The trick to storage is probably....better mana pools I'm guessing. Or more mana pools possibly.