I am not sure if you mentioned whether you are using round or square but go around to shop and ask if they have a "Ring Roller" like this
http://www.vansantent.com/bending_machine_z402.htm . Call around and ask if someone has one that can bend the tube for you. If you are using square tube you can also use a large sheet metal roll but it will make the tube a little oval. I have seen both used to bend .062 wall aluminum tube.