A couple thoughts....
First, the 'bite me' miles are just that, those miles where you have to draw from the mental games and tricks you learned through your training runs to get through to the end.
I can only think of one of my 20+ marathons that I enjoyed much or any of the last 10k. That was one race was the perfect storm of energy, zoning out and pace... I can find bits and pieces of good things in most of the others, but not the entire distance.
For the food plan... First, train multiple times with your idea. Many runners find that chocolate is very difficult to take on in the last miles of a marathon. Combine that with a fat load and, well just practice with them. I would look to a hard and sweet treat like sprees or something like that. I am a gel fueler. I find that it is in my best interest to bring 2-3 flavors of gels and randomly mix them pre-race. This mixing is so I do not consume the favorite in the first half. I reserve a special gel for mile 21 of the race. IT is kind of my goto gel. This would be where I would find your ice to work and work well.
Final thought, in general, the fuel you take on does little for a 20-40 minutes. There is no real sugar rush, only a mental rush. Taking in a special treat in DHS will not really hit the system until the finish for most runners. For that reason, think about taking on the special treat at the mile 21 or mile 22 stations. As you run the course through your mind, you will see that the mile 21 station has a lot of merit. Just following the station is the right turn up and over the DHS entrance road. Having the mental boost there can help pull you by the Green Army Man and down onto World Dr. The mile 22 station is on the up ramp off of World. It has its issues, but since the shade is there, that little hill seems a lot easier than the previous. By taking on the fuel at 21, you will fell the pick up in the BW or Epcot area.
Not sure I really answered your question.