I'm sure we can come to some sort of compromise situation, but what I'm more looking for here is a confirm/deny that backpacking or hiking solo is reasonable with a young child. Is this something commonly done or is this something that no one does and I'm just mistaken?

In regards to carrying him or letting him walk - right now I am carrying him most of the way. For 1-2 mile trips, it's not too much of an issue. He's a strong walker and can also walk on his own on some trails for a little ways. It won't be long before he can do a mile or two on his own, although it might take all day and that's ok. My SO has, up to now, not gone with me because he's not an outdoorsy person. He's never camped or spent much time outdoors. He is willing to try it out and of course I look forward to that, but his job has him traveling for weeks at a time, which is of course usually the time that I want to get out and take our son camping/hiking/backpacking because we are on our own.

I hear you on the issue with them running away, it's something I haven't thought of before. I'm usually camping in areas where it would be pretty difficult for him to get away, I'd have to not be paying attention for quite a long while. I realize it's still a possibility. But it's arguably more dangerous and easier for him to get away from me on a crowded street and no one ever chastises me for walking in town with him alone.

Thanks for the responses!