Opeongo, as you know, is a large lake - the biggest in the Park. Not that paddling it is impossible, but with the winds usually blowing in a southerly direction, the paddle up Opeongo could take all day. Algonquin Outfitters operate a water taxi and will take you, your gear and canoes right to the beginning of the Happy Isle portage in 20 minutes... you dont have to use the taxi both ways, since the wind is almost always headed south, the paddle down the lake might not be too bad.. But she gets very rough very quick.
Just something to consider allowing for more time to fish, and less time fighting the wind.