Here's a great blog by Steve Blank about the critical difference between a board of directors and a board of advisors:
Don't Give Away Your Board Seats
We work with companies to think through the progression, which is generally:
1) work with coaches
2) work with mentors
3) form a board of advisors
4) form an outside board of directors
Step 4 is only necessary with "significant" outside financing.
Probably a big difference between Silicon Valley (where Steve Blank is) and Maine is that here, a "significant" financing is probably between $300K and $500K, whereas it's probably 3X that amount in the Valley.
In other words, a decent size angel round or modest size VC round in Maine will lead to a requirement to develop an outside board of directors.