How are these Air conditioning voltage numbers?

I am set up as seasonal at a campground where I have experienced voltage drops as low as 105 during busy weekends. I was concerned so did some research. I ended up buying a Hughes Autoformer. Now my voltage never drops below 115. This solved my problem. The Autoformer was expensive but we'll worth it.
When plugging into a 120v 15amp circuit at a house the most common problem is the voltage drop you will experience if using a 12 or 14 gauge extension cord. A 10 gauge cord at minimum should be used.