With the power that you have on tap, to try and find a sub that is going to hold the line for you with that much power is going to be next to impossible. Tell the accountant that you can either do it once and do it right or do it wrong and do it two or three times and spend even more. If it means that you have to go without for a extra paycheque or two, suck it up and do it. The absolute worst thing you can do is cut corners when you have such a large amp. Total recipe for disaster.