Since you are providing the heat sink and the cooling, you need to tell us what the thermal conductivity is between the heat sink mount and the ambient air is. Again, saying something like, "my heatsink will be adequate" tells us nothing. Or, worse, tells us that we don't have to worry about power dissipation at all. That if we have to dissipate 1500W to deliver 500W, then that is okay because you have specified that your heat sink is adequate to dissipate the other 1000W.

 

Ok, weight is not an issue. I dont see such a circuit board being heavy no matter how its made.

The voltage cannot fluctuate. It has to remain constant to 2 dec places.
The remote turn on is wired like how a car amplifier is

If some1 wanted to help I would have sent them the device I had that I wanted made over and that itself would have answered most questions.

Wrt the heatsink the device I uses operates >80% efficiency throughout. There is no need for a heatsink that has to handle very high wattages of heat dissipation and it is a special designed heatsink that has high powered fans

The device I use cost less than 10 bucks and no matter what kind of current draw once within its capacity. The voltage stays constant to 2 dp. It stays barely warm even at max output when it is fan cooled.

 

Is that "two decimal places" the average or the instantaneous voltage output?