Well.......I went ahead and placed the batteries in the far left side (where the factory battery was). It doesn't seem to make any difference in the way that the trailer tows or anything. I was a bit concerned because between the solar panels and batteries, I have added nearly 150# on the far rear of the trailer.
I will weigh the tongue on Tuesday (Monday is jury duty). The trailer towed very well and there was no hint of swaying (which was my main concern).
Here's a pic of the final install on the solar panels.
