Are you truly wedded to those particular ingredients?
If you're not, I'd consider replacing the dumplings with a shelf-stable gnocchi:
- Boil a bit more water than you'd need for thinning out the stew (maybe 2x as much, depending on how many dumplings you're cooking).
- Cook the gnocchi in the water
- Add the beef stew
- Heat through
If the stew's a little too thick, add more water. If too thin, smash up some potatoes that are in the stew, and stir it in.
Personally, though ... I'd probably follow the first recipe that you linked to, but modify it to make it easier to prepare when camping:
- pre-measure the bisquick that you'll need into a sturdy, sealable plastic bag.
- add sufficient powdered milk as needed for the recipe into the bag
- (optional) add some spices or dried herbs to the bag.
when time to cook:
- bring the stew (with the extra water) to a boil
- add water to the bag.
- seal the bag
- knead to mix
- cut a small corner off of the bag
- hold a knife in your dominant hand, and the bag in your other one, then squeeze the bag slowly, then use the knife to knock off a dumpling.
- wait for the dumplings to cook