[Antennas] Mast question

Sun May 24 11:34:08 EDT 2009

Hi all, I wanted to know if some one can help me out with a mast
related question.
I intend using a single 18-20 feet galvanized iron mast with a base made
up of 3 pieces at 120 degree spacing ( similar to mercedes benz logo or a
 spread out tripod). additional support will include a tripod like
structure about 2 feet above from the base running to the spread out
structure. There will be at least 2 guy posts along the length of the
mast.
The base and the mast are not welded or joined in any way .The base support
structure will have a bearing sort of orifice to insert the mast into.This
way locally available sturdy bamboo can be used - if need be ( for a
 field op or emergency)
The question is - any suggestions/ modifications to this design ?
This entire structure will stand on the roof ( about 20 feet above ground
) effective height at feed point of antenna will be 40 feet more or less.
This mast will use an off center fed dipole with a ladder line.
Thanks in advance.
73's
VU2MTQ
Manish