12 Volt white ground wire?

Hey Guys, I have a 2008 16' Bambi that I just did a shell off to replace the damaged floor. I have it almost all back together and I am baffled about 1 wire. The power distribution box is located under the bed in the rear curbside area. I have the red (Positive) and the white (ground) wire that comes from the front area (Battery) through the floor next to the distribution box and they join in the fuse panel + and -. There is also a heavy white (ground) wire that is attached to the frame at the bumper area. I had this one marked but now its not. Does this white wire also attach to the negative post in the distribution box? I just do not remember where it went? Any help would be great!

Thanks,

RV Daddy