That looks pretty good. The only concern for those that would think about something like this, is to make darned sure the switches are capable of handling the current that will flow through them. If it were me, I'd get something that was at least 50% more than what you figure you will need. For instance, if your current draw is at about 20 amps, I would definitely make sure the switch can easily handle 30 amps.

Just remember that series devices are "voltage" devices in that the "available" current remains the same but the voltage is a factor of the number of cells in series, where parallel devices are "current" devices in that the voltage remains the same no matter how many cells you have where the current available is a factor of the number of cells in parallel.

CGr.