First of all a 5kW switcher is not something to take lightly. Looking at your test setup:
Those long wires will result in leakage inductance. That together with switching 200A is going to give you many headaches. Remember L(di/dt)? A inverter of this size needs careful planning and layout to minimize stray components, and adequate protection systems unless you like the smell of burnt semiconductor devices.
Sit back and do a few calculations ( sanity check 8O ) and get a picture of the task at hand. Push pull topology at this power using bipolar's will be a challenge to say the least. There are much more to this than you think.
BTW I'm not just talking, but from experience designing high power inverters.
Good luck!