I'd consider using a couple Sink Straps from GranQuartz and running them from front to back instead of side to side. I'd have to check the rigidity of the drainboard section to see if any other mechanical fasteners would be required. Or maybe use someBlack Mamba.

Thanks Joe, very helpful. The shop owner didn't know what straps were, had never used them, the guy doing the templates did. I don't feel like I should tell someone how to do their job, but when you've heard of better methods and practices, it is hard not to get involved. Owner said he just used clips and silicone. My GC will be happy to get involved and ask them to use something else.

I can order a bunch of straps and just have them here? The Black Mamba is out of stock!

Or just ask Joe to come install the sink since he lives in the area.

Yeah, that would make sense, but I have 10 sinks that they will be installing along with the counters and I have no control over the day or order of installations! I think I will get enough straps for all the sinks and have instructions printed out. I'll talk to my GC ... maybe I can see about getting Joe here to do the big sink with the drainboard. That will be the tricky one with a long stone rail along the front, so important that it gets installed properly. I'm going to templating at their shop on Monday for the kitchen counters, so I will talk some more about sink supports with the fabricator.

@Joseph Corlett, LLC, black mamba is out of stock, what other product would you recommend?

You want FGH adhesive. TryDiamond Tools please.