M.M.
I used a back pack with my sons and a sling with my youngest also.
The Kangaroo seems like a good fit.
Have you ever considered a simple ring sling? Guaze would be great for a trip like that. And with a ring sling and a wrap, you can move baby from hip to front, or put them on your back.
My vote is a Gauze, silk or light cotton ring sling or wrap. :)
We had a sick kitten who we were feeding through a dropper for days. We took turns carrying her. My youngest had her on his back for a while.
http://img.photobucket.com/albums/v242/eapoosmama/IM00083...
and one in the front http://img.photobucket.com/albums/v242/eapoosmama/IM00083...