When I made my ground panel mod I used a 30 amp RV power cord and cut it. https://www.loveyourrv.com/building-portable-solar-panel/ One thing I like about it is just the one cord and it's heavy so lies flat. For the entrance point, I used a marine port called a cable clam.

Another option may be a trolling motor plug as they can handle 30 amps. I used one for my air compressor port - https://www.loveyourrv.com/viair-450p-rv-12vdc-air-compressor-review-and-rv-hookup-mod/

A third option is this arrangement that I recently installed for my DC-DC charger - https://youtu.be/ww_4yhQPGwY?t=525

Ray,
The 30 A trolling motor plug might be the answer. I already have a 30A RV port at the front to power the trailer with the genset in the truck bed, and did not want a similar port tied to 12V solar. Is your 30 A cord soldered to the solar panel or does it mate with MP4 connectors. I will need a disconnect between the 30 A cable and the panels for storage. Thank you for always sharing your knowledge and experience.
Bill

You're welcome. :) Yes, I used MC4 connectors to attach the solar panel to the power cord.

Thanks for the mC4 correction. Bill