solar panel use

You should be good to go with the stock WFCO converter and an AGM battery. Where you would need to switch is if you were to go with an LiFePO4 battery. I made that change. That is because an AGM battery is still lead-acid chemistry, even if the acid is absorbed into a glass mat (thus, AGM).

Seems to me when I took out the board at the bottom of the WFCO converter/charger, the board was all I removed - it's at the bottom of the breaker/fuse array, and took maybe 4 screws and 4 wire connections to remove - just a board.

Since you have already replaced your WFCO with a Progressive Dynamics converter, perhaps you can tell me if it will fit in the same dimensions - the Amazon pics suggest I might need to alter the space where the WFCO is now.

What Renology told me was that the sum total of the parallel solar panels should be fed into a charge controller that can handle the total amps the panels can produce, and then you can clip the charge controller output to the battery terminals - they didn't mention it, but I suspect it would be safer to place and in-line fuse in the + wire between the battery clips and the charge controller.  Renology's 30 amp PWM Wanderer will handle my two 100 watt panels, and would probably handle a third.  The problem would be getting the panel wires into the charge controller - you might need special connectors for that, and for any extension wire used to get the panels in the sun.  If this would force you into a larger charge controller, you could disconnect the FR panels from the charge controller and connect the movable panels in their stead.

+1 to Colt. No problem at all connecting two independent solar charge controller to the battery. Renogy is wrong if they are saying you need to run all your solar modules through one controller.

If you wanted to run a single controller with different solar module sizes or manufacturers that OK too as long as they are nominal 12V modules and you are using a PWM controller. Don't do it with an MPPT controller with modules of different voltages, you will waste energy and confuse the max power tracking software.