I can't see which connector you are talking about, generally if there is wiring in the harness for work lights there will be 2 x empty connectors that they plug into. There should be a fuse in place in the fuse box I expect. Do not up the rating of the fuse, a fuse is there to protect the wiring, not the appliance/lamp plugged into the wiring. So the fuse rating stops the wiring from being melted if you overload the circuit by plugging in a ship's search light to your tractor.
What you plug in down the back will be limited by the circuit protection of the tractor.
If you need higher current draw than the recommended circuit can supply, you need to put a fuse at the battery and run a dedicated circuit to your search light with adequate wiring for the load current.
If there is a factory work lamp wiring option, it may well be ON whenever the key is on, so if you want it switched you would also need to wire in a switch or have lamps with built in switches. 85Hokie will have some tips and tricks for you I expect.