I also have naturally dark hair/eyebrows, and I've never found any method that I've liked, so what I've done for the last couple years is just get my eyebrows plucked before the con. Not super thin or anything, just thinner than my natural brows.
IMO, a lot of the painted brow methods look really unnatural, but this looks good with almost every color of wig (pure white is hit or miss... Looks good with my bob cut Elizabeth wig, looks kind of bad with my spiky Letter Bee wig). Plus, Peach has bangs that kind of conceal her eyebrows, so it will be even less noticeable.