Craig devised a "rear-view mirror" solution for keeping an eye on his daughter while she rode in the backpack:
My daughter is 3, but I thought I'd share a hack I used when she was less than a year old. I kept a small flexible mirror in a side pocket of the baby backpack (or in my pocket when using a sling or the Baby Bundler, which is a wicked cool tool in it's own right), in any case I had it handy. With ease I could use the mirror to check on the kid to see how she was doing in the backpack without resorting to neck-breaking contortions. It also let my daughter see my face, which she enjoyed. The mirror I used had rounded corners and a magnet on the back. The magnet was handy as I could keep it on the fridge when not carrying it around. I couldn't tell you where to go to get one as I stumbled across mine at a garage sale, but I imagine a dollar store or an automotive parts store might have them.