We don't use a crotch dangler carrier (like a Bjorn type) but I do cross LO's feet, as if she were sitting on the floor crosslegged and put her in our cheap non adjustable "Seven" Sling. She is 5 months old, but just under 12 pounds. She is kind of leaning back on me and can look around. It is not as secure as the normal way, but she has fun as long as I can hold her with on hand to keep her steady while we do stuff. My friend John told me about this way....I had no idea, tried it and it's a good solution for us when it is too hot for the mei tei carrier. She REALLY likes to look around.
Edit ~ Make sure Lo has good head control before trying this though