It says the coating is sensitive to UV rays, So if it is on the chassis would it still need to be top coated?
The sensitivity to UV is one of the deficiencies of some urethanes. These types of urethanes are extensively used for bridge coatings in todays maintenance markets. In the situation where Chassis Saver is used underbody, it does not have to be topcoated. This choice is left to the user. When not topcoated and exposed to direct sunlight (under a vehicle there is no direct sun) the product will degloss but it will not lose its physical properties and film integrity. It continues to do what it was specified for. When systems like this are used direct to rust in the maintenance market they are generally overcoated with aliphatic urethanes which do have UV resistance. The only people I tell to overcoat are those that have a high lift in a truck and there will be some exposure near the wheel well at least. Overcoating would generally be recommended with an acrylic or urethane enamel. NO clear coats over this.
Is the product available in California? Not all products are.