Charging Dual Batteries With Perko Switch

Hello WW.

I am rather new to the board (been lurking for awhile though). Just purchased a 2010 MB Sports TWB a couple months ago (had a SeaRay I/O). MB makes an awesome boat!

These boats come standard with dual batteries and a perko switch (and just about anything else I could think of). I have put the boat in a garage for the winter down the road from me, but it is not easy to go out and swap the charger from one battery to the other every once in awhile. I do not really want to pull the batteries if I do not have too (with the SeaRay, I would just pull the one battery and leave it in my garage on charger).

I have read multiple posts about charging and everything from the archives, but I am not very good at reading between the lines and I could not find a post that directly answered my questions.

So, the questions are:
Since I have dual batteries and a Perko Switch, can I use a trickle charger to charge both batteries at once? If so, how can I do that? Do I need the Perko set to ALL or do I need to rearrange the wires with + to + and - to -?

Any help would be appreciated.