No comfort insert. Vaseline on the rubber, and a clean shaved "fat pad".
This worked for me. I also tied a bandage around my ball-sack to keep my balls from entering the tube. But not the most comfortable. But everything for gains. I maxed out the hydromax 5 in girth in no time. I believe the comfort insert prevent you from gaining maximum girth.
In Wide Boy 7, I also winded a small strip of bandage at the base of my penis to prevent the mushroom shape from happening. Got more even expansion this way.