My dogs get much higher protein food than most cat foods. Most grain free foods will be higher than your average cat food. I've also fed canned evo which is the same ingredients for both the cat and dog cans. Just insanely expensive to do it for very long. We used taste of the wild at 32% protein for awhile and now use kent Native 3 at 30% protein so dogs can most definitely do fine on higher protein and "richer" food. It's only if they aren't used to it that you might have a problem.
I would boil any meat you have on hand with some of the other things mentioned for carbonhydrates like rice, oatmeal, potatos, sweet potatos.... Most veggies aside from root vegetables won't provide much nutrition since dogs don't digest them well and green beans are often used to fill up the stomach without adding any calories, carbs, or fat when you put a dog on a diet. You definitely need to use something with a bit more energy if you have to feed them without dog food for several days. If they won't eat the nonmeat portions of the diet soak it in beef or chicken soup broth instead of plain water.