Customer facing insofar that we'll likely want to raise some money and I'd like this person involved in that process
Sounds like the role is more than just as a developer, but someone who desirably is a long term part of the business and its growth.
I think the parameters slightly change for this type of position. In your shoes I would pitch the vision & culture you're trying to nurture as much as the technical challenges and career advancement that would come out of it.