Do you need to travel with the reels on? If not, you could just use ordinary pipe, glued on end cap one end and screw on or lockable on the other, secured to the roof racks/lader racks or the underside of the tray. Something like this http://www.adilockablecap.com.au/ (I have nothing to do with this mob, was just the first ones I found on the net.)
Hope this helps.
Phill