galnelson, If your trailer is registered in the USA, any state, you won't need a CSA certification to enter Canada.
The paint option is entirely your call but... After a few years, the basic gel coat (front & rear caps) will start to fade and be near impossible to bring back the original luster. This is the same for any manufacturer with gel coat only. The paint option maintains its original luster and is easier to maintain. Just my opinion from personal experience with the gel coat.