I am prepared to live with it but I am interested in seeing what can be done all the way from panel to battery to do better than last summer, if anything.
I can't help the panel heating that costs me about 10% of its power, so any improvement I can make has to be from panel to controller and controller to battery, and I can't change the controller itself.
If reducing voltage drop on the wiring and connections will be insignificant at the battery then it is what it is.
I was thinking of moving the controller to inside the rig where I can see the display and play with the buttons, but this would increase voltage drop from controller to battery. I can calculate what that would cost me in amps to the battery.
If I can predict the amps to the battery effect of reducing the loss from panel to controller as in the OP question, then I could figure what the total cost in amps if any would be and decide if that is "worth" bringing the controller inside.