[gotcha]

Originally Posted by MikeOConnor

Am I on a fool's errand here? or is there a better approach? or should I just go rent a backhoe and use the proper tool for the job...

I kinda think you answered your own question in the above part of your qoute. Time wise and when doing this you have to go to undisturbed ground before pouring any type of a footing which makes me in favor of the BH. Another words one can't put fill back in without having the proper compacting done and around my area an engineer needs to put a stamp of approval on it before the building permit will be signed. If I'm correct, a tower of that high has to have many other permits regading lights etc.