I would use the same type Heat Shrink Butt Connectors (Butt Splice, Insulated Waterproof Electrical Marine Automotive Wire Crimp Terminals) that I use for trailer wiring (like these):
https://www.amazon.com/dp/B08J7MZSX7?psc=1&ref=ppx_yo2ov_dt_b_product_details
since I have the crimping tool and heat gun.
But solder and heat shrink would be fine (If you don't have the tools and don't want to make the investment) ...it just would need a bit more care in waterproofing.
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