West Marine Wall paPER & Below counter sink
West Marine has a product...called "Six-10"
It is an epoxy binder.
It will glue ANYTHING. Word of caution, do NOT use it anywhere you ever want to lift, remove or have future access to.
I have used it with great success in this very area, travled from FL to AK, back to CA....no issues at all. The application can be a bit tricky. Not out of the tube, but id you have serious wrinkles....a small strip of 1/8 ply and some clamps if it is on your leading edge....or if in the corners you can use speing loaded curtain rods...small or lg.
As a closing thought, those of us that have the below counter sink...the one that is held on with clamps and is forwver droppping down or needing center support.....This is THE product. place a very god bead on the sink edge, pull the sink down once to assure that you have contact all the way around. ( add more if you dont) Then replace the sink, clamp in place with the original clamps and place the temp support in the morning. you will NEVER have any seperation or support issues again.