You will find it is easier to center your boat if you dont put the trailer too deep. I keep about half my bunks out of the water, this way the boat will slide on, but will not shift side to side and usually doesn't float back off. I also bought the light brackets to keep my lights out of the water, which is nice because thel ights that came on my trailer weren't of the submersible type.
Short guides are for the birds, especially if you are fishing with current. My trailer has short guides and it is a bear to load my boat if the current is up. I am in the process of trying to greatly lengthen my guides, and also narrow them to fit closer to the boat. Definitely go long!!