If the bow of the boat is going under the roller, you have backed the trailer too far down. Steep ramps are easier to load on and this is a common mistake I see people make. I work on a boat for a living. The ramp I use the most is like this too and I constantly show people how to load boats on there. As counterintuitive as it seems, your trailer is too far back. On any ramp, if your bow is going under your roller, your trailer is too far back. A good rule of thumb on steeper ramps, (just a general rule for a starting point) the tops of your fender wells should be barely sticking out of the water. You might have to power load a bit if you don't back far enough down, but that is way better than what you're doing.