You didn't say which sink, but I presume it's the kitchen sink. It would be helpful if you included your year and model of your coach in your signature line also. :-)
On our kitchen sink, the stainless steel sink was separating from the Koradon (or marble like) countertop. I found that WRV never installed retainers at one end of the sink to hold the sink up against the countertop. I just applied a little silicon sealant to the gap at the top edge (under the countertop) that opened up if you pressed down on the sink, and then installed retainers under the sink to pull it up against the countertop.
I couldn't find any "retainers" made for this sink installaton so I cut and bent as required some 90 Degree angle brackets you can get at the hardware store until I had sufficient lift when I screwed the bracket into the wood strip around the bottom of the countertop so that the cut end lifted the sink up to seal against the countertop.
At one end of the sink WRV did install retainers, so you can view those and get an idea as to how this can be done. The only thing that might stop you is the pretzel contortions that may be required to work under the sink. :-(
I can take a picture if you have a problem.
John & Carol Randolph
2005 Alpine 34 FDDS
2006 Jeep Liberty