questions about battery disconnect wiring

This isn't real clear on what you have done and want to do. If you are relocating the battery to the trunk, then look at where the battery is connected in the engine compartment, you will need to run a 0 or 1 gage cable from the battery (now in the trunk) all the way to the front and connect it just like it was before (to the starter). For a cut off switch, you would put that somewhere along the new cable's route and have the new cable go to one side of the switch and then the a cable from the other side of the switch to where you were going (the starter). You will need a battery relay feed (the smaller red wire that normally goes from the battery to the relay); since your battery is all the way in the trunk, you can connect a 10 gage wire from the main stud on the starter where the battery cable is and run it up to the starter relay (thus replicating how it is normally); you will still need the 10 gage wire running from the relay down to the starter as it normally is. If you mount your disconnect on the firewall or inside the engine compartment, you can run the battery relay feed wire from the one side of the disconnect to the relay.

Just google "mopar starter relay wiring diagram" and you will see how all of the wires/cables go, then just imagine that the battery is located in the trunk and thus you will need longer cables. You could run a 10g wire from the battery all the way to the starter relay if you wanted but you do not need to.