my overhead table carrier is just balanced on top of the 2 rear cupboards, then 2 small scews at the rear , at each end where hinges are...threw the wood and into the metal lip your headlining clips behind
you wont be able to do this as you have too many windows for the rear cupboards
1 thing i do strngley suggest....dont think you can pop another table on top of the table carrier and then brake ....i manged to put a lovely dint in a NOS coleman fridge as the table slid off the holder and down into the rear of the bus
but as jonolly says....small screws do the job.....mines mostly held in by gravity and hope, and nothing moves around much