Strapping the can to the outside will work, as long as you have it empty or with lighter things in it (as Just Sit suggested). The downside is that you will have to unpack and repack the can each day, but if you try to strap it to the outside full of food it will be too much weight too far away from your body to carry comfortably. Another option is to try to pack other items around it on the inside, and strap other gear on the outside of your pack, but it sounds like you’ve already tried this and that it didn’t work for you. When I last hiked the JMT I carried a larger pack and was able to fit my can sideways in my sleeping compartment. My husband carried the larger Bearikade which did NOT fit, and he was constantly experimenting with different ways to carry it. If you do end up strapping the Bearikade on the outside, be careful not to scrape it when you set it down, especially on granite. Although I’m sure the scratches we now have on the outside of our carbon fiber can are merely cosmetic, they are nonetheless disconcerting.
Kanga