Changing bunks & roller(s) on 1900XR?

[RonnieT]

I have the Factory 2x4 rectangle frame-made trailer that came with my 1989 Maxum. There is only 1 Vee-type roller on the trailer and it's under the transom.
It does not contact the transom, it's about 1.5 inches lower than the transom and is not adjustable.
The only other roller is up at the bow at the winch.
I have only 2 bunks one on each side near the rear and are both 10 long carpet covered 2 x 6s. they need to be replaced and I will do that.
Was wondering if I need to add another 1 or 2 Keel rollers on the cross members that have none. it looks as though the keel has suffered some scraps because of people not knowing how to load or unload or blowing wind/waves. If I add the rollers is there a good one I should use to do that and how are they adjusted? touching, not touching, load-bearing?