Awhile back at a local hamfest,  there was a fellow (QRP'er) using one of these...this thing was 30 meters long, and if you tipped it over horizontally,  it only drooped about a foot from end to end....twist locks, painted black.....   

I remember reading the literature about this mast....you can build a pull size 40 meter loop with four of them..

I'll look around and see if I can find the URL for this outfit....I remember the name but now the address....

KU4VE