Dual batteries have their advantages if properly done. Use two switches and two charging jacks (one for each battery) and plug the second battery/switch into any unused channel in the receiver. Do not use a Y and try to get by with one switch. The main thing whether you use one or two batteries is to use a high quality (heavy duty) switch and heavy duty wiring and a minimum number of connections; i.e. avoid extensions if at all possible even if it means soldering in longer wires between the existing connectors.