I have the exact same trailer, but in gal. I have never driven my boat up I prefer to walk it up with rope and using the winch. Its a bit of a pain when its super windy but then again I dont go out when its real windy at least not on my own. You are right, unless you get it pretty much perfect straight its easy to miss the roller and scratch the gel coat.
After doing a bit of research I too have changed all the keel rollers to red rubber. I had the two rear most rollers crack and fall apart on me under the weight of my boat (and yes I have the side wobble rollers pushed up tight taking some of the load).
The red ones cost me about $140 from one of the online boat trailer spare sites (not cheap!!)
With the red rollers on the boat doesnt roll off as easy as it did with the hard blue ones though, I have to sink the trailer further into the water, getting the back tyres of my car wet!! 8(
@zmk1962 do you know if this type of guide can be purchased anywhere? It looks like it would provide better support to the stern. My boat is extremely stern heavy for some reason. I have the wheels moved as far back as they go and still only have about 50-100kgs down force on the hitch.