Whenever I've sold an RV in preparation for moving on to another one, I've left enough water and sewer hoses, etc. for a basic park hookup. Electrical adapters, extra hoses, etc., go with me to the next RV to augment or replace whatever comes with it. I've never had to store them for more than a week or so, but longer wouldn't be a problem. Twice we've swapped our existing mattress to the new RV, replacing it with the "new" one in the old RV. We've even swapped toilets twice now. Of course that means having the new RV on hand before parting with the old one.