The trax comes with a clear undercoating my friend has a 99 silverado he had undercoated with the clear undercoating when it was new, the truck to this day looks new underneath.
The clear stuff is good, as it is, I just wanted to add a little extra to coat the bolts and anything that might rust.
It takes about 2 to3 cans to coat all the trouble spots good, the middle of the vehicle never gets any slop so don't waste your time or undercoating it, it is just the spots behind the front and rear wheels that get the abuse of salt and slop.
This is the method I have been using on new metal cars for the past 10 years, when I trade my cars they still look new underneath..