Given nbryan's real-word experience with 430 lbs on a similar tractor, and the cautionary advice from others, I'm beginning to think I've over-done it. My final calculations put the total weight at 1280 lbs. My 'barrel' was a 28" tall section of a 1/4 ' wall commercial propane storage tank, which weighs around 190lbs on it own. I shouldn't have thrown in that extra concrete we had left over from a recent pour. I may go back to 600-700lbs.