Wow, talk about cutting it close!!
If it looses connection with the controller or the battery gets really low, it'll initiate RTL. In both cases, this can be overridden by pressing Fly or another flight mode, assuming in the case of a controller loss, the connection is reestablished. On the controller, make sure your antenna are pointed DOWN and out a bit. Having them pointed up will severely reduce the distance before it'll loose connection.
If this were to happen again - it's out over water and, presumably, it looses connection and goes into RTL, just head your boat towards Solo, as you get closer and the controller is able to connect again, just press Fly to cancel RTL. This, of course, assumes you know where Solo is. I'll admit to loosing sight of mine sometimes when I'm focusing on the phone to frame a shot - it's not out of sight, but I've just lost track of where in the sky it is. Especially over water where there's this possibility, it would be a good idea to have at least one person tasked with keeping visual contact with it.