I am trying to reduce the power dissipation of a P-Channel MOSFET high side switch. So my question is: 

* is there any way in which this circuit can be modified so that the P-Channel 
MOSFET will always be "fully-on" (triode / ohmic mode) no matter what the load is?

**Edit 1**: Please ignore the on/off mechanism. The question remains somehow the same: how can I always keep V(sd) the smallest possible (P-MOSFET fully on / ohmic mode), independent of the load so that the power dissipation of the MOSFET is minimal.

**Edit 2:** The switched signal is a DC signal. Basiclly the circuit replaces a switch button.

**Edit 3:** Voltage switched 30V, max current switched 5A.

![enter image description here](https://i.stack.imgur.com/8PxZ6.png)