P-channel MOSFET ZVS Flyback Driver
You can make it with one MOSFET (paralleling them increases current capabilities), you just have to make sure you keep within it's ratings. Something like this circuit only uses a single IRFP450:



You could drive from the high side using your P-channel FETs, but I'd keep it simple and lowish power/voltage to start with.

Obviously be very careful with the high voltages ;-)

For a P-channel version, you can just swap all the polarities around from a design like this. You should end up with something like this (disclaimer, although it simulates okay, I have not tested this, so check everything carefully. The parts are not recommendations, just what LTSpice had available):