Glad to see someone continuing to get out even with a little one...I hate seeing people become "tied to the house" when they have babies, it seems to happen a lot but it doesn't have to be that way as you have shown. And she will grow up being comfortable outdoors and enjoying it, which is a great gift to give any child. As far as the sled goes, you could run the rope through two 5-6' lengths of PVC pipe or electrical conduit (1/2-3/4" diameter), attach two carabiners to the rope ends as close as possible to the pipe ends, and then pull it by attaching the carabiners to the hip belt of your pack. That will keep the sled from running into you on downhills. The stadium seat is probably a good idea to give her some support, if you can secure it in the sled.

PS: She's adorable! :-)