I have a Craftsman 42" lawn tractor, purchased new in 2005. Mine has a B&S engine though. I haven't had issues with removing the blade bolts, but then in Arizona we don't get rust.
I use a 1/2" drive ratchet with a 9/16" socket (six-sided). Yes, these bolts are tight, and supposed to be tight, are fine thread and supposedly specially hardened, and are right hand thread. I disconnect the spark plug wire for safety, put on work gloves, and hold the blade with one gloved hand and the ratchet in the other, and pull the bade and ratchet towards each other. I have never needed to try a 1/2" breaker bar or my 1/2" drive electric impact wrench.
Nowadays, I do have a Harbor Freight lawn tractor jack, which I really like, so I can actually see what I'm doing, better than wedging a 2x4 under the deck to access the blade bolts.