I do something similar here and have taken to ordering 5 lb bags as well!
The only tip I'll offer is to not suck TOO MUCH of the air out. The first time I did and when I reopened the bag, it was a BLOCK! I had to spend a lot of time "declumping" it. Now, I just suck air out until it JUST starts to squeeze it and then seal it and stop the vacuum. Keeps the air off of it but still allows it to not cake too bad.
18.5", 22.5" OTS
Large BGE (chambersuac's)
The Fiery Furnace (chambersuac's)
Big JT's Smokin' BBQ Competition Team