A really good question !!!!! And one to think about.
When my V-20 reaches the "bow stop", which is actually a roller, the hull is sitting squarely on the bunks and bow support. Should I continue to crank the winch to cause the roller to, well, roll.....then I would actually be lifting the boat off its supports and placing undue strain on the bow eye and winch strap.
I, too, experence minor chaffing from the bow 'roller' but dismiss it to flex in the aluminum trailer. Besides, and occasional waxing removes all evidence of any chaffing. I do keep the 'roller' adjusted to the point that it is free to turn by hand.
I'm anxious to hear other's responses.
FWIW....Ed in 'ol Virginny