You can splice in prior to the front of the trailer if you want with the step down splices just stagger if you want, just more connections. https://www.westmarine.com/buy/ancor--step-down-heat-shrink-butt-connectors--P015982408
Or you can put one of the non metallic electrical boxes and mount on trailer to house a bus bar for the connections. Seems like a lot of excess work but you only have to do it once. I just have my ground by the coupler.
https://www.homedepot.com/p/4-in-x-...C-_-NavPLPHorizontal1_rr-_-NA-_-100404097-_-N
Or you can put one of the non metallic electrical boxes and mount on trailer to house a bus bar for the connections. Seems like a lot of excess work but you only have to do it once. I just have my ground by the coupler.
https://www.homedepot.com/p/4-in-x-...C-_-NavPLPHorizontal1_rr-_-NA-_-100404097-_-N
