The bolts have come loose on my center mounted bowrail, therefore I need to drop at least the center panel of the headliner in the cabin and front berth, can anyone help on how to get to the bolts so I can tighten them.

I had to do that on my searay some years ago. The only way I could get to those bolt heads was by slicing the headliner. Fortunately it was only 1 bolt that was leaking. So after recaulking and tightening, I carefully sewed the liner with matching fine thread.It looks OK but not first class.
I hope you can get the liner down intact without that last resort.

You will have to take it apart.

Got it done today, all I had to do is pull a 1,000 staples, tighten the bolts and restaple. Oh ya, tear out the glued in hatch cover trim rings, buy new trim rings and replace, Oh and lets not forget, trim rings are special order, and won't be in for a week or two or threel, Great fun!!!
So I guess I lied, I won't really done for few more weeks. But then again its a boat and boats are never really done. You all know the drill.