I caught a 5 lb. largemouth on my 3 weight yesterday, from the bank. You can handle a decent sized fish, though of course not in heavy cover. I had a 3x (8 lb) tippet on .
I used size 8 and 10 gurglers on gurgler-pop style flies up top, and mostly gill buster or wooly bugger types lower down. An #8 upside down marabou muddler is great too. The bass yesterday hit a size 8 "Plan B", as seen at the website below. It is hard to cast heavier flies from a canoe, at least for me as my rod is only 7'6", but it can be done.
http://www.warmwaterflytyer.com/patterns3.asp
Russ