Then you’re gonna need a lot!
If you’re aiming to use the amazon led panels, I’d look to fit them at about 50 actual watts per square foot. Just make sure you get something with a good balance of blue to red wavelengths so you can use the same lights throughout.
If you don’t mind spending a little more money up front, you can get into a more efficient cob setup or do something with quantum boards. They’re going to put out a lot more par per watt, thus requiring less watts to achieve similar levels. Start up costs will be higher this way, but cheaper in long run when energy costs are considered.
I think either way you look at it, it’s going to cost more than you had originally planned. Using half the tent now and building on your grow later is probably a good option for you. Or you can save some money building your light fixtures too.