Yes. For decades, actually. The board won't hurt it but it definitely isn't necessary.
You don't need to remove them from your camper, either, but unless you have some type of tender (solar, plug-in, etc) you definitely want to disconnect them, either via a disconnect switch if you have one or disconnecting the cables. Almost every camper these days has small parasitic drains - the CO2 detector, sometimes a radio, OneControl receiver, etc. 300mAh isn't going to hurt anything over a week, but over a winter it can definitely kill a battery.