Mounting the second solar panel was then rather simple. It was a matter of repeating the physical mount, that is to say, using stainless steel bolts and nuts to ensure that the panel was not directly contacting my frame. Then clipping the leads and attaching standard automotive spade type connectors. The leads on the solar panels are shockingly short, apparently only really long enough to connect one panel to the next, and I ended up mounting the second (and eventually a third) panel upside down, alongside the initial panel. This worked out without having an inch of cable to spare! But hooking up my meter afterwards showed me pumping 9.5 amps of current into my charge controller - hopefully enough.
It's been a few days now, and the batteries are slowly coming up to a higher charge. Yesterday wasn't so good, as it was overcast and raining most of the day, but up until then they were ending the day with a greater charge than the day before, so that was gratifying. I still think another panel and more batteries are in the plan for this fall yet.
Then I ripped four of these "beams" in half to place at the very bottom, and very top of the box, to ensure a level surface. It was a fun matter to fit the beams together, in the manner of the toy log cabin sets that Kenny has played with. Of course, it wasn't long into the project before I realized that my accuracy in measuring was not as great as required, and most of the beams required further work with the saw and chisel on the notches before they would fit together nicely. That, and wailing with a mallet.
I put in a less substantial floor than in the Tardis, trying to use up some poplar planks that were rapidly warping over in a corner of my sawmill area. I also built a small interior wall to separate the batteries from the charging equipment. While I'm sure the offgassing of the batteries is very small, I do want to be sure to keep them away from potential sparks. I sized the box to hold at least six batteries comfortably. More if needed.
Hopefully soon I can cover the box and move it into position - I really want to get started on bringing in my winter wood!