Thanks, everyone. I'm going to try and pick up some 6 gauge stranded wire along the way. No one has the wire reducers in stock. But I can leave the wire a bit long and add them later.
I really appreciate the help. We're leaving in a few hours for Jackson and will stay in Green River UT or Provo (if we are "energetic") tonight.
You could leave a few inches long and add later. If you can not find them I would do the following. Push a couple of inches of 10 gauge into the 6 gauge, solder all together and cover with heat shrink tube. Done neatly this might look better than a reducer.
Edit: to clarify cut two inches of 10 gauge and push about 1/2 inch into the 6 gauge. Solder this 1/2 inch area. and cover this area with heat shrink tubing.
Edited by billharr, 18 October 2015 - 07:13 PM.