<p>This could become a "big" production. Firstly, if you need "help" your probably unqualified to do the job. Not being rude, but honestly, shoots like this require experience to successfully accomplish. Based upon the budget and physical circumstances (limitations) I'd probably start thinking cherry pickers, lift trucks or scaffolding. You'll need a couple of 2000w/s power packs minimum - forget silks or umbrellas - at these distances they won't create a visual difference to hard light. You should, for a professional look use at least a 4x5 camera with adequate resolution for recognizable faces.</p>
<p>If you find this hard to believe - I recommend doing a test with your 7D and one of you lights to prove it. Evaluate the images based upon what ever size print their after and the sharpness and resolution present to recognize faces. I would just say no, there are folks who specialize in this kind of work with the equipment and experience to painlessly pull it off. MHO</p>