I'd vote #2 provided the battery disconnect does remove all or practically all of the loads. Some RVs have things like LP detectors powered up even with the disconnect open. If the non-disconnected parasitic loads are more on average than the solar can make up, you'd be heading for a dead battery.
As this is outdoor storage in a relatively cold climate, you could also just fully charge and completely disconnect and leave the batteries over the winter without trouble. They won't self-discharge down to worrisome levels over the winter (self-discharge is much slower in cold conditions than in warm ones). But, since you have the solar, there's no reason at all to do this since leaving the solar connected will largely or completely counteract any self-discharge.
