"bullet proof and solid" may be the key here, as you likely want the 8" gravel drive sitting on something that isn't going to move around, such as frost heaving where there is water in the subsoil below the gravel.
When you say"somewhat level and drains fair", those are descriptions that would be warnings for a drive that may not be "bullet proof and solid" in the future.
If you dig a trough 8" deep in poorly drained clay soil (maybe an extreme for your situation) and fill it with 8" of stone, rock, or whatever, you likely will not have good luck in the future. Frost heaving can tear up about anything. Your local roads will give you fair warning of what you can expect.
My drive sits on glacial till (terminal morraine of the glacier that left here a few years back and dropped lots of rock and debris with not much clay) and doesn't move between freezing and thawing spells. But drives on clay will move a lot.
In short, it is going to be difficult to give you a prescription that will fit your situation. Local soil conditions will dictate what you need to do. Possibly find someone who knows how to build a driveway that will work on time and materials would be my recommendation.
When I was going to put in my drive 35 years ago, I had this idea of where it would go, but hired someone to do it. I couldn't believe what he was doing and where he was going. Ripping out trees that I wanted to leave, and going back on a slope 30' from where the drive was to be. All in all, and in the end, it is a good thing he knew what he was doing (because I sure didn't) and put in a drive that has been great for all this time. The right slope, banking, ditching to keep water away, and base to make a great drive (even better now that I had asphalt laid down a month ago).
Wish you luck and a great drive. /forums/images/graemlins/wink.gif