I'd call and check with the Hilton on Blue Lagoon... they used to have a big bass tournament out of that hotel but that was many years ago. It won;t be inexpensive, but they may even still have a ramp and dock.
Its only a 10 minute drive to the public ramp, the ramp is actually only about a 200 yards the way a crow flies but you have to go around.
There is a couple motels on perimeter road that have drive in garage rooms, one has a heart shaped tub with lights and mirror;s on teh ceiling. Maybe you could back the boat into the room and park the car/truck outside... actually the sort of cater to the hourly rental crowd that don;t want their car to be seen if you know what I mean.
Other than that nothing outside in that area is safe unless there are armed guards.