I used to use twisty-ties but now use these   (You need to Login or Register I like to get a bright color so if they fall on the ground they are easy to see. Also use them to attach fishing poles & net to gunnel & painter ropes in place & a ton of other things.

As far as the backpack goes... I have seen it done very several times, I have 2 external & 3 internal frame packs I use for hiking & hunting trips, they are way nicer to carry. The biggest downfall to them is the way they fit in a canoe & the fact they ride too high to allow carrying the canoe with the pack.

Have a great trip.

Troy