RE: windshield cracks when leveling
Bottom line, if you 'crack' the windshield while leveling, you are using ONE jack more than the others and creating a torque on the frame causing the crack. You need to move each jack TOGETHER as much as possible or move them one at a time a SMALL amount, to keep the overall frame from creating that torque. These behemoths were never designed to take a lot of stress that way, and I have my suspicion that there are no real factory engineers designing these things.
good luck