My winter storage up till 2 years ago has been batteries in... disconnected via RV switches (last RV had both chassis and coach disconnect, current one only has coach), jacks up... had no power available.
I checked on it periodically - never had a need to charge batteries... ran engine/gen for their own sakes a few times over winter.
I asked the dealer years ago when I bought first RV about jacks up/down for storage - and UP was recommended... Seemed to make sense not to expose the nice shiny shafts to the snow/salt of Michigan... Never went back to relook at it honestly. Been a lot of discussions about not having tires off the ground with leveling jacks on the forum...
My recent winter storage (last 2 winters) has been jacks down, slides out, plugged in... at an RV park in central FL with me in it! Works very well.
Now 'winter storage' applies to the house in MI... until someone buys it.