most bag these days are designed to carry a laptop. i imagine you want something padded and fitted for your camera body and lenses. you might need to find a 'camera bag manufacturer' to get something that is designed for a dlsr camera. it would most likely have a laptop compartment.
you might run into room issues with your shoes and clothing. you might be looking at something larger than a carry on i was thinking you could get some
MOLLE pouches designed for your lenses and hang them outside the main bag. then, have your body, laptop, clothing, shoes, etc., in the main compartment.
good luck in your search, have a fun trip.
Edit: looks like the above post is a good solution. not sure how much clothing and shoes you can cram in there, though.