Either solder and heat shrink a loom together, or use waterproof connectors such as AMP or Deutsch connnectors and make up a loom. AMP will be cheaper than Deutsch, Deutsch are good though.
Anything external and really in the elements, when I heat shrink, I like to fill the heat shrink with silicone, for a good waterproof joint.
Your going to need to splice a loom together anyway, to get four separate feeds, it’s just weather you want to be able to change a light easily in the future or not? So a combination of soldered and heat shrink loom, with waterproof connectors to join the lamps?