Is it really necessary that these rollers be that tight? Have they worn the gel coat down in the points of contact? Many boats have the guide ons, which are more of a reference. I can see if you launch most of the time with a heavy beam current that these could be very useful. I would guess that as the stern of the boat is still floating as you run onto the trailer, that there is some force straight down when the boat settles on the trailer, as you remove it from the water. Is that where the wearing occurs? The rollers look to be above your "scum" line, but I can understand that you brought the bottom paint and boot stripe up further.