You should be worried about current / amperage !!! Switches rarely run high current devices or systems. The switch and the wires must be able to handle the current draw of the appliance. Match the amp draw of the lights to the wires and switch ( and probably relay). If these ditch lights do not draw much current you may be ok, but you have to find how much current the lights draw in total.
A switch in a 4runner rarely runs the current for a device through the switch, in a 4runner, a small switch simply toggles a relay which can handle the current for the device. So you are not running the appliance through the switch you are just using the switch to engage the relay that
can handle the amperage.
Switches just short 2 wires together using contacts, throw it one way the connection is made, the contacts touch, the other way and it is broken.
A switch has throws and poles, a single throw means it has one movement, an up and a down position (or side to side depending on how you mount it), a double throw has an additional center detent (off) meaning it has 3 positions. A single pole single throw switch means it has 2 lugs and one movement. unless it is a special switch (which it may well be), most switches that are double pole are simply 2 switches side by side. 2 of the poles are on one set of contacts and 2 on the other, they are generally always seperate so that you could throw a single switch and get 2 different circuits connected, such as a light on one set (side) of lugs and a buzzer on the others. all from a single throw double pole switch. In an air conditioner you might throw one switch and trip a relay that has double poles and it powers both the compressor clutch and the fan. But the switch is not passing the current to the A/C system, just enough current to engage the relay. A single tiny little switch can turn on a entire city by using relays, but it may not be able to handle the current a single bulb.
you can use an ohm meter to figure it out. A generic switch will not have a proper color code, you have to find out which lugs are shorted when you flip the switch.
Toggle Switch: Precise information and various applications of Toggle Switchs