Good call on the larger wire from the combiner to the controller. MO is why lose voltage everyday because of small wire sizes. I have a double run of 4 AWG from the combiner to the controller.
When all is secured and connections are good, I'd suggest to experiment with covering a module or two. It would be interesting to see how the controller handles the different modules.
BTW, a reference from the battery mfg might be a good thing to have regarding charging levels and such. Deka used to have really good info about battery treatment and such.