You should call Rustoleum to get their take on it. They should be familiar with their paints and how to handle it. I have never used that product, but have used other products from Interlux, Pettit and Awlgrip. After preparation and cleaning, it is usually best to roll on several thin coats than one thick coat for starters. Secondly, while rolling on the paint (and following up with friends to tip right after), you want to do the entire hull. Don't do one part, go take a coffee break and then come back to finish it. You want to have that wet edge from start to finish for best results. Then let the paint flow out on it's own. If you are getting sagging, then you are using too much paint. If you have a lot of orange peel or stipple, then you could be using a roller not designed for the job. There are different roller covers that eliminate orange peeling. Different paints have different hardness after they dry. I don't know about Rustoleum. Alwgrip is very hard and not easily repaired. Awlcraft is softer and more repairable. They just introduced another which is also repairable. There are compounds used for freshly applied paint and other compounds used for older paint applications. 3M makes a number of abrasives for sanding out sags and orange peel from bad paint jobs and the grit gets very small. Again, I'd contact Rustoleum and ask them about how to use their products. The worse scenario is to sand smooth what you've done and start over. Good luck. It can be frustrating.