I have not seen any aftermarket lights with a mating plug for the FlexBed 12v connections. What most are doing is using a pigtail to connect to the FlexBed 12v connection and splicing the lights to the pigtail. This is how I installed a 12v auxiliary power outlet (cigarette lighter plug) in one of my cubbies.
You can also cut the FlexBed 12v connector off and splice directly to the wires.
If you need a usable plug, it would probably be best to install "standard" one. There are various available. From a simple cigarette lighter plug, like the one I installed, to more complex ones with USB and volt meters.