In MMB it says check in at Miami opens at 1100 and when passing the concourse around that time last year they were setting up tense barriers.

I am on this flight next month and staying at a hotel in the airport vicinity. Would there be any problem in checking in my hold luggage, getting my boarding pass at around 11.30 and getting the airport flyer bus to the South Beach to meet some friends for a final lunch before heading back to the airport around 5pm.

Would they ask if I was intending to leave the airport and if so would they refuse check in?

Other options are left luggage at MIA whilst at the beach or leaving it at my hotel and going back there en route to the airport. Would prefer not to do any of these.

Alternatively could I go through security, go to the Admirals Club then simply leave the secure area after a while. Would this cause problems when going back through security.