I had a similar need with Las Vegas a month back- we were flying back to our hometown for 2 weeks. Ultimately, our options came down to 3 things:
1) Getting a campsite and just leaving the camper parked there (benefit: can leave camper plugged into electric; con: cost)
2) Finding a storage facility (benefit: cost; con: no electricity)
3) Parking it at the airport parking lot (benefit: convenience; con: cost, but still cheaper than a campground)
Your options will be similar- just change "airport" to "cruise terminal".
