The thick bar is harder to grip because you can't close your hand as much. However, it is easier on your wrist and very effective because when you go back to an olympic bar your grip will be stronger. Since, I train at home I don't have a thick bar but I made an 2 inch thick axle out of a 7 foot long steel pipe and I have a 2 3/8 pipe to go over that which is 4 feet long. Very hard to use this for deadlifts and clean and presses. It will reduce the weight you can use but it is still effective.
Good luck with the PL contest where are you competing and what federation?
Discipline makes you mentally and physically tough!
Currently making everything stronger!!
Once I stick to the program I am going to get really strong.