no. It won't. The data are quite precise, and the negative flavor effects of underpitching were well-known empirically before being well-documented starting the mid-19th-century (remember pasteur?).
If you don't believe me, believe someone like dr michael lewis, professor emeritus, university of california, davis:
As for details about what dr lewis is talking about, wyeast labs - the makers of the yeast the op plans to pitch - says that underpitching leads to excess levels of diacetyl, as well as increases in higher/fusel alcohol formation, ester formation and volatile sulfur compounds, further leading to high terminal gravities, stuck fermentations, and an increased risk of infection. (
source)
see also
here.
There are many things homebrewers can just rdwhahb about, like hot-side aeration. Yeast pitching is not one of them.
edited to add: Op, pitch two packets and you'll be fine. While you're out getting your extra smack-pack, get some more sanitizer, a pound of dme, an airlock and a bung to fit a brewpub growler (you
do have growlers, right? If you don't, hang your head in shame.
). Now you have the "ghetto" equipment - should be under $10 - to make starters. Search for instructions on how to make starter wort and go nuts.
After you've brewed your starter, i strongly recommend pitching slurry, not starter. It's a simple thing to decant most of the spent starter wort, leaving enough to swirl into the yeast and make a runny slurry the consistency of pancake batter. That's highly concentrated yeast compared to a full starter. So you can pitch far less volume than starter calculations often call for.
Anyway. I won't hijack your thread anymore. Pm me if you've more concerns.
Cheers!
Bob