I've had 2 flats over 5,000km on my road bike. One was yesterday when I ran over a massive nail. I don't think any tire is going to stop a 4" nail. The other flat I got I have no idea, sometimes it just happens.
I don't think generic Cyclocross tires are not going to prevent you from getting punctures any better than a normal 23c or 25c road tire, however, there is a tire i can recommend that is bombproof:
https://www.schwalbetires.com/bike_t...rathon_mondial
I've run this tire for a couple thousand km's and I have read people riding them 20,000km without a flat around the world. You can get them in 700c X 35 & 40, that would fit on a cyclocross/adventure/gravel style bike if you choose. However, would I go this route just to avoid flats on a road bike? No way, the amount of fun I have on my road bike far outweighs the amount of flats I get.