easy just tie in the number 1 or 2 switch to the hot side of the relays, no need for additional fuses or relays since they are already built in, only way to go IMHO
And to get the power under the hood, there are 4 pass thru wires, (read owners manual) that you can tie into the output side of the upfitter, and make it so its under the hood, then from there run to the power side of the solenoids.
Generally i like the control IE wide open throttle switch ect to be on the ground side of things to complete the circuit
what are you using to control the nitrous?