Let's see what advice can I give, well if you make a brick then my Brick will have a brother.
All I've ever used is 2%. I don't bother with blending, but that's not to say I won't try it. I do press to 20 pounds, use my chart to find the correct psi for a larger wheel.
For a 5 lbs. wheel I'd use 7 gallons of milk, that's what I had in my notes after making a 5 gallons wheel that was 8" diameter and 3" high.
I could actually give useful advice but me brain hurt, been a long day.