I know many of us have Hibiscus in cham cages. Don't know what a "Luna" Hibiscus is. Check the safe plants list on the resources tab. It probably is OK as long as it hasn't been sprayed with anything at the nursery or shop.
I just saw one of those lunar hibiscus at Canadian Tire on sale. It is an awesome plant with lots of huge flowers, it is also a perrenial that will come back in the spring so I'm thinking it would not be as hard to keep thriving as the tropical hibiscus'. What did you find out about it veiledowner 87? safe? I'll try doing some research too when I get the chance.