You have as much right to use a public launch ramp as any other boater. And like other boaters you should prep your boat in the lot before you go to the actual ramp. It can be tough to get things rigged if your kayak is on your car. If this is the case use wheels. Get every thing ready then head for the ramp. If your PA is in the back of a pick up then get rigged and just back the truck down. I use the sides of the ramps on busy days. So basically have your shit together and take care of business when on the ramp. We've all seen "That Guy" on a ramp; can't back a trailer worth shit, his motor won't start, can't find the plug, ect, while 5 boats are waiting to launch. you get the idea. Had to show this.
http://www.youtube.com/watch?v=FwaETCl_ElM
Saw one of these at shelter island ramp when I was a kid. Mike