Isn't that what Budweiser does? Zym got it right. After rereading it, I didn't have my plan stated very well.
Whatever Budweiser is doing, they are doing it consistently! (How's that for a non-responsive answer?)Whew! I feel better knowing what your plan is. I use plastic buckets that have levels marked on them. I keep forgetting that carboy's don't.
FWIW, I plan my beers out at 6 gallons due to dead space and possibly too much boil off. If anything, the OG comes out higher and there is no problem topping it off to bring it to volume. The last batch was a Strong Scotch. The recipe was supposed to be 5 gallons at 1.072(ish) and when it drained into the fermenter, it was 1.082 at 4.5 gallons. Topping it off to 5 gallons got me to where I needed to be.