campmanfromSD,
No problem with leaving it as it is. I would recommend shutting off the main valve, though.
My personal preference, though, is to try to have it near filled, just in case we need to use the rig during the winter months. If I don't need it, then it's all ready to go in the springtime. A few years back we had a freak blizzard at the end of October and power was out for the better part of a week. We were able to do our cooking in the motorhome using the propane stove and microwave (using the generator). Plus the propane keep the motorhome refer cold.
But no harm will come from it being left at any level of fill.
~Rick