Pull prudently with FEL chain grab hooks. FEL is not designed for force to be applied with the tractor in reverse. That is why no tractor brand offers bucket hooks as a factory option.
For moderate and heavy pulling get a $20.00 clevis Grab Hook for the rear/center drawbar. You can pull without damage to the tractor from the rear/center drawbar, which is attached directly to the tractor frame.
Also loading FEL like you have, you may want to consider rear ballast.... Anything over about 400 pounds in FEL tends to make rear of tractor VERY LIGHT... like with no brakes unless in 4WD...