Not sure if this forum is still open to discussion but I recently came across the exact same issue. I was looking for safe padded camera like storage for the Mavic and accessories, plus extra space. I purchased 2 LowePro backpacks for comparison: the Flipside Trek 350 AW II and the Whistler 350 AW II. Both have plenty of storage for your UAV equipment as well as a separate area for spare clothes, etc. The Whistler is significantly more expensive but is made really well, with some bells and whistles. It’s fairly heavy in comparison to the Flipside Trek but the Trek also has padded storage and spare space. It your only gear is your Mavic the Whistler will offer too much space and weight but the Trek just barely fits my Mavic and accessories. There isn’t one right answer, but if lightweight is a priority over weather resistance, than the Flipside Trek 350 or 450 will solve your issue