The only portage issue that I see as a problem is a clogged put in or take out area of the landing.  If I can reasonably inject myself into the crowd on the portage I will land somewhat off to one side where no one else is and next, quickly move my gear and kayak a few yards up the trail and off to the side of the path.  Then proceed to get organized and merge into the traffic.
I am a three tripper too, so at the end of the portage I will stack my gear and kayak several yards back from the put in so it will not be in the way when I am not there.  I also use the leap-frog method of covering longer portages; when I set down my gear I make sure it is well out of the portage path but not too far off.  It is hard to lose my stuff as it is in bright colored packs: purple, red, yellow, etc.  If your pack is green or camo you might overlook it if it is too far off the trail.  On the rare occasion when another group's packs might look like mine, I keep a close eye the gear going into their canoe in case someone has picked up my pack by mistake.  I have had to retrieve my gear out of other folks canoes a couple of times when someone mistakenly loaded it.   
Personally I have no problem sharing the actual trail with others, stepping off for whoever is heavier loaded than I am.  It seems the BWCAW sort of promotes keeping groups segregated on the walk as well....on a busy portage that would make it take all day to accomplish!