I found an interesting piece of software on the Trylon Titan web page:
It's the program Trylon use to determine whether a selected tower will be
adequate for a combination of proposed antenna loads. You'll need to input
the antennas' wind area and other parameters regarding the physical
arrangement on the mast.
I suggest you read the instructions and thoroughly understand them (and
the caveats) before you apply them to a proposed configuration of TRYLON
TITAN TOWERS (emphasis intended.) If nothing else, you can see the effect
of increasing antenna mounting height on the reactions at each section of
Gene Smar AD3F
P.S. Don't forget to include the wind area and weight of your mast.