trailer adapter splicing- connector

[CADjockey]

Good Evening!
Just a quick question. It has been a while (long time) since I have had to do any kind of wire splicing.
I am rewiring/making an adapter cable (6-pin square plug to a 4-pin flat plug) for a recently purchased used trailer. The trailer has a 6-pin plug but no electronic brakes have ever been on the trailer. I have a decent multimeter to verify good continuity.
My question is what kind of splice connector would you recommend? I have some crimp type connectors, and some shrink tubing. Is soldering recommended for this application?

 

[Chuckster in NJ]

I would check out e trailer for some "plug and play" wiring so you don’t have to splice wires.
Without knowing the vehicle manufacturer here is a sample for a Chevy.

https://www.etrailer.com/t1-2008_Chevrolet_Silverado.htm?gad_source=1&gad_campaignid=13871914504&gbraid=0AAAAAD_vMtl-_yfI4fz8bBxb0zvHbU19Y&gclid=CjwKCAjw6rfSBhAqEiwA_yocppx4hKcqjHf-QdRyWwdUUiLFdy3grNCrigI1qbUWiHp29Bz1x6B_0xoCG0YQAvD_BwE&Redirect=8

 

[yatg]

Cut off the 6 pin connector, get a 4-flat stub, use **** crimp connectors to connect the stub.
Stagger the crimp connectors so they're not all bunched up.
Slip on some wire loom for a finishing touch.

https://www.amazon.com/CURT-58030-Trailer-Harness-12-Inch/dp/B001GN3BSI/?tag=atomicindus08-20

If you ever decide to put brakes on it, use a 7-round like normal people do.