If you want the deer to wear your piezo tweeters on their ears then you can use the small very low power amplifier IC with tiny piezo speakers.In other words it won't perform as well as the mosfet amp?
But the small amplifier IC probably cannot drive your large high power piezo tweeters.
The Mosfet that has a lower on-resistance does not heat as much but it has a higher capacitance that slows down its switching so it gets hot unless it is driven from a low resistance.What about the substitution of the FQP7P06 for the FQP17P06
Transconductance is how much output current swing is caused by a low input voltage swing. It doesn't matter in your circuit because the Mosfets are switches, not linear amplifiers.what ever forward transconductance is?
It is one cause of heating.9.3S vers 4S
is this related to the capacitance you are referring to as to a reason the P channel gets warm?