I don’t disagree with the posters who say that it’s entirely possible to ride a Ninja on dirt and gravel. But if I was buying a commuter bike, I would want something that could handle that road after (or during) a little rain and there’s a big difference between riding smooth gravel and riding in sticky mud. I’d also be gritting my teeth everytime a chunk of gravel kicked up and scratched my fender, fairing, etc.
I’d be thinking the same things in choosing a car for that route. I might lust for a low-slung Lotus, but the road is probably more suitable for a small SUV or Outback.
If I were in your shoes, I’d check out a nice dual sport like the DRZ400 or a LKR 250-650. That way you’ll look forward to hitting that dirt road, rather than crawling your way through it.