Hence the reason why all the loudest bassracers use tons of cone area and don't have insane amounts of power per subs... Just like you said about Mackey's setup, it can be done for a short period of time but it will not last.
But to the OP - I'm guessing you're planning on running the woofers w/ 5k @ 1ohm x 2 channels?? Why not instead of smoking your woofers just run it 2k @ 4ohm x 2 channels for the time being, and get a more efficient box built for the time being... Then figure out a more proper combination of woofers that can handle that power daily (like 4 12s or 15s), then wire it down to whatever u want and run the 10kw daily... Right now you don't have the electrical or woofers to run it daily and not burn something up.
Actually tried to be constructive with this post.