Hi @UBERMAN2552Sorry if my english is not perfect, but im from holland so please forgive me.
Reading your post, and understanding only the nutrient question coz in europe we work with liters instead of gallons xdxdxd
I would go with the tripart system of GH/Terra Aquatica ( thats the new name )
And I would go with RO, and add cal+mag myself. ( like you suggested yourself )
For some stability in ph + / ph - its smart to add cal+mag till 0.2/0.3 E.C and then add your other nutrients.
I have the perfect .excel file for you, where you just enter the start ec. And the amount of water ( ltrs tho ) And it will tell you what you need to add from what nutrient in what stage.
Let me know if interested ( a pic of what im talking asbout is on my profile )!
Can I also have a copy of your excel sheet in Litres :)