Clip it off and use shielded solderless connectors.

 

Those connectors you have are very high quality. The rubber O-Ring seals them from water. Look closely for a manufacturer's name or logo. Contact the manufacturer and get mating connectors to put on whatever lights you buy.

The crimp-on style are very much subject to water entry, which won't cause a direct problem, but will lead to corrosion and poor electrical connection in time. If you can't find the mate to the connector you have get something similar - a four-conductor trailer connector is designed to keep water out, although they're not much better than the crimp-on. True you only need two connectors, but having four won't hurt anything, and you can use them in pairs for twice the connectivity.

 

For lights to be effective off the road you want them to be as high as possible. Light bars on the cab work well and if the are mounted at the back of the cab there is less light and glare to deal with when driving and trying to see what is ahead. Zero gain if lower than the hood of the truck.

 

Usually these connectors are 2 pin ( i think it is positive and negative). But the 4 pin connector you have can support ON/OFF and other functions( like RGB, flash etc).
I believe this connector you have can connect with a multi function light or strobe light.
But you should always check with the user manual to see recommendations for what type of lights you can connect.

Below is the male connector of one of my lights. Hope this info helps.