From reading some comments....
He can't work from the top down if he can't get to the top first.
Fill dirt is the last choice for building a road. Requires lots of compaction and work. Grading off dirt and leaving an undisturbed base is the best beginning. You have an acre at the top. So it sounds like you have ample room to cut in a gradually sloping road/ramp straight up into that hillside (which sounds like the route you want to take) which will leave undisturbed base all the way from bottom to top.
You don't want gravel for a road topping. Gravel is round. Round doesn't lock together. Each time you drive over round gravel your tires push it around and to the sides, leaving two tire paths with a crown in the center and crowns on each side. Gravel requires more maintenance. You want something crushed with lots of jagged edges so it locks together and doesn't push around when you drive over it.
My father used gravel and it didn't work well. Then he tried crushed limestone. It worked better, but it still pushes around. The best thing we've found so far is slag from steel mills. Looks like lava rocks. Locks together and just doesn't move around at all when driven over. However, that isn't available in lots of locations.
Crushed asphalt tends to lock together pretty well, too. Wonder why your gravel guy wants you to put gravel on top of it? I'd put the gravel on the bottom and the asphalt on top as well.
What's your soil type in that area you want to put the ramp in? And what degree angle is the existing slope and what degree angle are you aiming for when complete? I know I asked that earlier, but it really helps for people to understand what you're currently dealing with and what you want to end up with when complete.
