Thank you!
I didn't glue all eight boards at one time. I glued the inner four boards first and the next day I glued on the two outer boards on each side for a total of eight. So only four boards were glued at each time. I think this dramatically simplified my glue-up. After each glue up, I scraped then sanded. With the exception of a few divots from scraping to long in one spot : ( she is very flat. The top rests on the aprons nicely all the way around.
I don't think (although I am still a neophyte at this) you need a flat surface. If all your joints are at 90 degrees, with good even clamping pressure it should come out flat. My top during both glue-ups was resting on bar clamps on the bottom, with bar clamps also spanning accross the top.