Magnetic Switch.
https://www.amazon.com/Kwikee-379404-Surface-Rectangular-Switch/dp/B000BRF5X4/ref=sr_1_4?crid=3K129UIMX865S&keywords=magnetic+tailgate+switch&qid=1640649205&sprefix=magnetic+tailgate%2Caps%2C455&sr=8-4
https://www.amazon.com/DaierTek-Flange-Switch-Nickel-Universal/dp/B081MTFTDL/ref=sr_1_12?crid=3K129UIMX865S&keywords=magnetic+tailgate+switch&qid=1640649205&sprefix=magnetic+tailgate%2Caps%2C455&sr=8-12
https://www.youtube.com/watch?v=77t1UW4Qc7g