by the rules, staying overnight is prohibited. but it's ok to come after 12am when the new day begins, you are paying not for 24h stay but for a calendar day. we spent the night 6km away and came here 5:30am to start the hike, parkman was already there. 19,50€ for a motorhome is too expensive for a low season. the way to morske oko is an 8km asphalt road, it was the most boring thing ever.