here is the link for what US boaters are REQUIRED to do:
http://www.cbsa-asfc.gc.ca/media/facts-faits/096-eng.html
before you take 'hearsay' advice, i suggest you carefully check with customs on both sides to understand the rules that are now in place.
if your are 'dropping traps' in US waters, you will still need a non resident US license. i can't fish your side without a canadian license, you should not assume you can fish this side without a US license. get stopped on this side with your canadian license and see what happens, it won't be pretty.
the international boundary means that when i travel N, i am entering a foreign nation. when you travel S you will be as well. these regulations are getting far more strict than they used to be, get informed before you get stopped, end of soapbox.