So, after a long hiatus, prompted by Gibbie's new found ability to ride behind an adult on his "tagalong" (meaning he hated the old trailer and I didn't know how to carry Ezra with the tagalong) I finally mustered up the courage to just try something. Lo and behold, it worked!I just tie Ezra, who is is now four years old, on my back. I don't do this much anymore, as he walks everywhere, but it worked just like always, and doesn't hurt when I'm leaning over biking, as it tends to now if I tried to wear him while walking any distance. It's similar to biking with a heavy backpack, which I am used to. Ezra loves looking over my shoulder, and we can all three of us can talk much better than when I was hauling them in the trailer because they are closer. I think it's quite safe and feel more comfortable in traffic than I did with the trailer. Plus, Gibbie is contributing to the ride! He can pedal along, and push hard on hills. He's really helping now!
We have biked like this to several places including our church, which is about five miles from home and up quite a hill! Another disadvantage which kept me from doing it for so long is the lack of storage space--I can't wear my backpack. This should be easily resolved with a generous handlebar basket and a rack over my back tire to support panniers. Maybe we could even put a rack on Gibbie's tagalong? I can't use a rack with a crate on it, because the tagalong runs in that space over the wheel.