Found some pre-packaged formulas with these ingredients, sound right?

Dextrose, sodium chloride, sodium bicarbonate, potassium chloride.

Dextrose Min 50.0%
Salt Min 10.0%
Salt Max 12.0%

Potassium Min 0.60%
Sodium Min 5.25%
Sodium Max 6.25%
Sodium Bicarbonate Min 5.00%

Oral rehydration solution

http://en.wikipedia.org/wiki/Oral_rehydration_therapy

Can't get much more basic than that if making your own.

It is oral. Your recipe is similar. Both are crucial treatment
for small children with dehydration from diarrhea. The orange juice makes it more a little more flavorful and adds a bit of
potassium, which can be helpful as long as there is enough sodium too.

Try Morton's "light salt"- half sodium chloride, half potassium chloride. A bottle cap of that and one of baking soda in quart of water, along with something to hide the ick if you really want.

Sugar, salt, baking soda, water and a packet of unsweetened KoolAid works wonders as a low cost, easy to carry electrolyte replacement. Keep the dry ingredients in a small tube or other water proof container, add them to the water, have patient drink as much as they can.

The chemicals will replace the electrolytes, the KoolAid makes it palatable.

Try some with some lemon-lime flavored KoolAid and then compare the taste to original Gatoraid some time, an amazing similarity.

This homemade mixture kept me out of the hospital a year ago with dysentery. It didn't stop it, but it did prevent dehydration until the dysentery stopped. You actually develop a taste for it after a while!

1967-Ft Benning Ga..full gear "forced" march..i thought i would drop..something came to me about salt tablets and rehydration from something i had read or heard about so i took the burn packet from my first aid kit and added to my canteen.if i recall it had sodium bicarb and salt..i not only finished standing and in good shape but was able to drop and do push-ups before being allowed to rest.at the time i don't think there was anything going around about electorlyte replacement..

what is the baking soda for?

What NightHiker said. I use 1/4 teaspoon per liter of water. Not enough to do any damage but enough to do some good.