If your tent poles won't fit inside your bags and you decide to strap them to your rack, I'd advise sewing some loops (similar to the top of some panniers) on your tent pole bag and then threading your rope or bunjee cord through the loops as well. This will stop the poles from wiggling out from under your rope and getting lost along the way.
Also, a thick rubber band (like those from broccoli and lobster) around the opening end will also give you a little more security in the tent pole area while on the bike.