I'm no expert on yeast health, so I've always just deferred to the experts. My understanding is that such a small amount of yeast would be overwhelmed (and stressed) by the reproduction that would be needed for such a large volume by such a tiny amount of yeast.
A couple of things I do (I don't do no-chill) to use RWS since it's so much cheaper is just freeze any extra wort that I have. I'll boil it on the stove first, before freezing it. I can either add water to get me to 1.040, or boil longer, if the wort isn't already in the 1.040 range. Some of my wort is in the 1.050 preboil range, so it's just a matter of boiling it for 15 minutes and adding water. I freeze it in small quart pitchers or containers, then when I want to make a starter I just thaw and boil it in my flask for a few minutes.
I have even done a small mash just for starter wort, filling four containers after I boiled the wort.