I did a solo from Irvine and looped around west down to Royd/Gammon pre fire (2016).  We didn't fly over that area on our last two trips up there so I can't be much help there.  However, I would take stock in Claire's advice. I would think there would be quite a few trees down from the fire itself and then you have windfall and snowfall trees coming down over time.  I waked a portage (without boat) from one of the lakes to the west of Irvine to a river that was not cleared after a fire.  I literally had to crawl under trees and climb over trees.  It was interesting to see some of the blazes on the dead/charred trees still standing. I have some pics of that area if your interested in what that looks like. Campsites need to be cleared as well.  On the plus side you can get some pretty good views from high places!   BTW the fishing on that trip was crazy good! 

Stay safe.........