We didn't install this farmhouse sink, but the concept is probably the same (we used the kohler 36 inch stainless sink). As per trebouche's advice, we used a HUSH harness system. It attaches to the sides of the cabinet, and criss-crosses under the sink. My sink is very square, and so we used some metal simpson angle things to distribute the weight (so the weight of all that water isn't at a single spot). If you want, I could take photos for you. It seems really solid.

geny:

I could find no recommendation to cut the sides of the sink cabinet in the manufacturer's installation instructions:

Here is a link that might be useful: 200

I don't see why this sink wouldn't work with a 36" sink base cabinet.

We are thinking about the Kraus Farmhouse sink, 36" (actually 35-7/8), and were wondering if a 36" base can be made to work. Or, we could use a 42" or 48" cabinet and use the extra space for trash, etc. We will have no disposal. On another note, my wife is tall and we are planning to raise the entire counter 3 1/2" above standard, to 39" (I did this in my current kitchen and she loves it!). I put a platform made of 2x4s on edge under all the base cabinets.

I second Treb, I think you were only meant to cut the cabinet if you have an existing front. You don't, you should not be doing any cutting here.

I installed the same sink (but 36") and am entirely confused by your question. Additional plywood between the sink cab and dw? Cutting the side? I'm not sure why you thin either of those are necessary.

We just installed this sink last week. Had to cut the front of the cabinet to modify but not the sides.