Coming from a manufacturing family, I certainly understand the gut reaction. However, If you're producing so many, why are you looking for smaller volumes of adhesive then ? You must go through several tubes a day if your a large manufacturing shop.
Not knowing anything about you're setup, I have to ask - how many tops are going out every day ? What's the largest(widest) sink ? If it's kitchen sized, isn't it impossible to mount those tabs in the center, front and back ? How is that then supported?
Isn't transporting tops with sinks attached inefficient as well as more costly ? Certainly it's more risk of damage. Who bears that responsibility, you, the shipper, or the end user? I get that a specifier might be driving this show, and that's what they want. Perhaps you might sit down and educate them on how to be better / faster / cheaper ?
At some point I saw a hybrid system of sorts. I didn't file it away since it seemed to costly in time and materials but I never ran the numbers beyond a dozen tops. It used a special cutter to route a dovetailed like keyhole or pocket that received the special mounting bolt for a mechanical bond. Then the hole was filled with epoxy , stabilizing the the whole thing. I doubt it makes sense for many shops on a financial level though.