Will the JL Freedom Top be amenable to insertion of an interior metal support system? There are several systems that can be installed in the JKU interior so that a roof carrier system can be added. Can the JL rear seats be removed?
I'm not sure how, if at all, your desired interior metal support system and a roof carrier are connected: either literally or as concepts/ideas of yours.
Perhaps this link to Mopar's new roof top carrier for the JL might be useful to you.