what are some key things to consider when making a bikepacking rig?
I added rear panniers back onto my bike for my last tour because I had to carry some extra group gear. Boy did I regret that...having the extra weight on the bike was one thing and riding to protect the rack and panniers from damage was another, but the real killer was that when I had to hike-a-bike my rig up steep techy singletrack that left rear pannier was right where my hip wanted to be. The result was some very awkward body positioning and much less smiling on those sections.
Next time I will carry a heavier backpack or do whatever I have to so I can skip the rear rack and panniers on technical terrain. The trade off for getting weight off my back was not worth it.
OTOH - if I was just riding dirt roads [ie GDR style] the rear pannier setup would not have been so bad.