I use a similar method to launch solo. I sometimes tie a long bow line to a dock cleat then back in and let her go. Get out, snug up the line and tie off the stern.
I have also tied a bow line to the trailer Winch post. With this method I may have to step in the water to get the line (cold water here).
Also, I have a 2 gallon plastic garden sprayer with water and some salt Terminator (like salt away) mixed in to spray things off. I keep a garden hose in the pickup if there is a fresh water faucet at the ramp.