My trailer has bunks but I also added a set of these:

 

 

The lights on the guides were something I added myself. No matter how strong the current or crosswind is, the tall guides keep the bow from going too far past center. They are also super helpful when backing the empty trailer down a steep ramp where otherwise you have no idea which way it’s heading.

First time someone tries to load a boat where there's a good current and a steep ramp, they will wish they had those.