Boat Trailer Side Guides

[Tin-Can]

I am thinking about adding side guide polls to my boat trailer.
The purpose is to help speed aligning the boat to trailer when putting the boat back on the trailer.

What are your thoughts about using them?
Can they harm the boat if they are rubbing against it while in toe?

Is it good or bad to have the side bunks touching the bost while in toe?
Mine don't touch if the boat is centered on the trailer.

Dale, I have had side guides on both the boat trailers I've owned since 2004. My current trailer bunks and side guides are all 2x6 Trex decking planks. They won't rot like wood or even pressure treated wood. They are wrapped with indoor - outdoor carpeting. The side guides are mounted to the trailer and are just at the height where the carpet wrapped Trex is about 3 inches below the gunwales, and about 3 inches away from  the side of the hull on both sides. I can nose  the bow into the end of  the trailer and even if it isn't perfectly centered on the bunks at first, it will kind of "bounce" back and forth off  the guides and end up centered right up on the bow stand, even in a strong cross wind.
If the guides are well carpeted, and you have an aluminum boat, they shouldn't hurt the boat at all.  For either a fiberglass or aluminum boat, be sure any bunk or guide mounting hardware is well countersunk into the supporting material and wrapped well with carpet. Secure the carpet on the outside of  the guides or bunks (away from where any boat surface may touch). I used stainless steel 1/4" Hex head self tapping screws about 3/4" long. A bit more $, but they won't rust and break off or leave rust marks on the carpet.