Yes, I agree that none of the valves used in a closed center hyd system need a relief in a closed center hyd system.
If the valve does have a relief, just set the valve relief to say 3000 psi so it will never open, and the pump relief will dictate the relief pressure.
You might say how do you do that with the tractor relief set at 2250 psi. Well, when it gets to 2250 psi, just crank it down more about one full turn should work. Maybe use shims if you have to.