Sounds like an amazing trip! I haven't taken a safari but I have traveled with my REI Big Haul duffel quite a bit and it's versatility and durability is pretty hard to beat. What I love about the Big Haul is that it is super versatile, if you want to carry it as a backpack you can, across the shoulders, or in your hand via multiple handles. There are also daisy chains, attachment points, and loops in abundance so you have the option to customize your carry solution as you see fit. Personally I have a wheeled duffel that I am able to strap my duffel to for moving through the airport efficiently. I am not aware of any duffel system that is designed with a sleeve in place so the perfect system may require some customization on your part (potentially extra straps or just practicing with your duffel and rolling luggage until you are able to get it dialed). I hope this helps and have an amazing adventure!