For your consideration here are some other antenna mounts.
http://www.ronard.com/Tripods%200703/4712.html ,
http://www.ronard.com.
Buy the ronard antenna mounts at solidsignal by typing the word ronard in the solidsignal search box.
Here is a light weight aluminum , lay over tower , do antenna installation and adjustments , standing on the ground.
http://www.palcoelectronics.com/pe300.aspx