Does your pack fit inside one of those garment bags used for suits? They have a long generous zipper that makes it easy to get stuff in and out. No matter how you bag the pack I would still take off straps and put inside the bag or duct tape the straps so that they do not flop around. Also, remember that most airline have a 50 pound single bag limit. And butane gas cannisters or white gas are not allowed.

If your airline charges a lot for baggage, you could consider shipping your stuff UPS or FedEx ground to your destination. For large packages FedEx ground is cheaper.