Guess that means its time to see if I happen to have a p channel mosfet or pfet in my box of unsorted components.

A random MOSFET you find in your junkbox is unlikely to be optimized for your requirements.

 

I just want to check before I order something. I don't think I need a driver circuit to drive an IRF610 because the transistor is controlled via a square wave. I'll try it later tonight.

 

I don't think I need a driver circuit to drive an IRF610 because the transistor is controlled via a square wave

But that is precisely why you may need a driver.
The square-wave has to rapidly charge and discharge the large gate capacitance of a MOSFET during the transition between on and off. If this is not done rapidly then the MOSFET dissipation will go up as it spends too much time in the transition region.

If you get a MOSFET with a low gate capacitance (gate charge) then you may be able to drive it without a driver.

 

The gate capacitance is in the datasheet, right?

 

The gate capacitance is in the datasheet, right?

Right.
The value usually used for switching calculations is the gate charge, which is related to the gate capacitance, but is different because of the non-linear gate capacitance.

 

The input capacitance is 200 pf and the output capacitance is 80 pf. Is it low enough to not need a driver?

 

The input capacitance is 200 pf and the output capacitance is 80 pf. Is it low enough to not need a driver?

Likely.
Does it have the current capacity and a low enough on-resistance for your requirements?