I have tubed calves a long time ago, but never a bird. Ideally I'd rather not learn on a a small bird like a pigeon, especially on on with a recent crop trauma, since I wouldn't want to make it worse if I hit the wrong spot. I was thinking of a pasty diet like oatmeal... What if I only give the electrolytes for a day and then try something like oatmeal. Would that work?
FYI, at least right now the poop is normal, so I hope that is a good sign.
If your bird is still eating normally then there should be little need to tube feed especially with such an injury. I would space out the feedings so that she gets just as much as she normally eats but not all at once so the crop doesn't fill at least for the first week. extra vitamins etc may help heal faster too.
i would just give her her normal food (if its like chicken feed) and water it down to make it softer.
Cant help you on the antibiotic suggestions but i use "super booster" when my chicks get sick. http://www.drugs.com/vet/super-booster-can.html