Nice Job 996!!!
I definitely think this is the best solution for a P38 winch, far better than the OE winch mount which permanently robs the vehicle of approach angle. It also means you don't have to lug the winch around for the 99% of time that its not going to be required.
My own setup does not allow a sufficiently powerful winch fit for the P38 for serious off roading. Having done a winch install I'd strongly recommend this to anyone considering adding a winch.
One suggestion would be to put a heavy duty recovery point on the box iron under the winch box. The existing point is very strong but I wouldn't use it for kinetic recovery.
Well done!!