A pony wall for the back of the peninsula is a pretty standard solution for this problem. And that support on the DW end should be examined to be sure it's really the 1 1/2" panel you think it is. That would be two 3/4" panels bonded together, and if so, then that's sufficient if they run from the counter height all the way down to the floor. That would be sufficient vertical support, but it would not be that stable just to be there on the end. You probably also want a filler in there at a 90 degree angle to provide additional stability. Basically, building a box out of the 3/4" panels with the filler in the middle, and then running enough horizontal support at the rear and front so that it's not wonky. Or just do another pony wall and cover it with some skins. It's probably cheaper (and sturdier) to do it that way for sure. You can always turn the studs sideways to use less space.

We got rid of our pony wall/raised bar. We added 12 inches of display cubbies and cabinets (haven't added pulls yet) and gained a nice wide prep area. There's 19 in. of counter behind the sink, but a little splash still reaches right to the edge.

I meant to add that a 12 inch overhang without barstools will look unfinished. Either build out the back and panel it so there's a structure under the 12 in. of granite or add cabinets if you need storage. And who doesn't?

We didn't use barstools on our old peninsula because the dining room table was just 3 feet away. So imagine your overhang looking like this. Those 12 inches without barstools underneath were useless and an eyesore. It's what got the remodel going.

may flowers: I LOVE what you did to your peninsula. I actually was thinking of doing somewhat the same thing with bookshelves but I was afraid that it would be too crowded since my kitchen is very small. Here is a picture of it, pre-reno, but the layout is pretty much going to remain the same. There is a cabinet to the right which is the blind corner. It's usable but the plumbing goes through the bottom. I can pull that forward and balance it which a book cabinet on the other end I guess. My problem is I can't come too much forward because the patio door is right there (as you can see in the photo).

hollysprings: Thanks for your input. I will probably do what you suggested and have them build a pony wall and maybe shorten the countertop a little bit. That seems to be the easiest solution.

may flowers: Are the cabinets behind your counter custom carpentry or are they stock cabinets? They look very custom.

They're custom. We didn't do a deep corner cabinet--just built on 12 inches along the entire back. The plumbing is inside the sink cabinet.

The inside of the cabinets are cherry so they look like a dining room cabinet and not kitcheny. They hold wine glasses and china.