I have a 48qt cooler and 30lbs is right at the limit I can get in there. So 40 lbs in a 10 gallon cooler would not work.
If my grain bill is over 30lbs I take out some 2-row and add some light DME during the boil to compensate the gravity.
On Tap:Foreign Extra Stout, ESB
Fermenting: Fools Gold IIPA
Up Next: Oatmeal Stout