There are lots of very experienced folk here at QJ. I have not trod the portage in question but if you keep checking back someone else has and will very likely lend a helping hand. Good folk in these parts when it comes to helping out.

In my world double portaging is very much the norm. There is no duplication of effort as you are not carrying the same items across twice ;). Triple portaging is not out of the question for some folk either especially if your goal is base camping and you want lots of "goodies". The portages on average are fairly short compared to hiking in the mountains hour after hour. If you insist on carrying heavy loads so you don't have to double so be it.

My suggestion would be to plan on doubling especially your first time in. Then evaluate your gear selection for future trips and having had a better feel for the lay of the land you can better understand what needs to happen to single safely and effectively. The flip side is if you plan on singling and have very heavy loads the fun factor may decrease and you might set yourself up for a fall and get hurt. And for what? So you could save 15 minutes? Besides, the walk back unencumbered through the woods after being mostly on the water is very nice. You get to feel and see and hear the wind in the trees (and the skeets buzzing in your face ;D). This is also a good time to take pics.