Help with input protection circuit and reverse polarity protection

[teslinius]

I am designing an electronic load rated for 150V 25A max, i completed most of the schematic the only thing i'm not sure about is input protection, i only placed a varistor for overvoltage protection, i checked a bit how other electronic loads are built and i noticed that they have some power resistors and film capacitors but i'm not sure what kinda circuit are they making, also do electronic loads usually have reverse polarity protection?, and if they do what kind of circuit it is because at high currents like this i would need a beefy mosfet for protection which increases the cost

[drdm]

https://circuitdigest.com/sites/default/files/circuitdiagram/Reverse-Polarity-Protection-circuit-diagram-Using-P-Channel-MOSFET.jpg

This is the standard circuit for a MOSFET RPP.
And yes, you'll need a fairly big transistor, but that's the cost of doing business  .