How to attempt a quarter pipe at an obstacle course?

Super afraid of heights here also. That being said, I also had to overcome this issue, skateboarding, when I was younger. The best thing to do, in my opinion, is to just keep trying it.

The more you attempt it, the more comfortable you'll be with failing. I'm actually being technical here, you'll develop techniques that will function as tools that you can use when you fail. These tools will become second nature which will cause the fear to subside, albeit slowly, at least in my case.

For the longest time I tried to drop-in to a 10-foot quarter pipe. Not super tall, but tall enough to be scary to me. I was around 15 at the time, and little kids would come up and do it while I was still standing there trying to collect myself. This was embarrassing for me, as everyone was watching as I picked up my board and chickened out. The thing I was missing out on though was everyone else's perspective. They just saw this kid walking up and trying to do something that scared the shit out of him, over and over again. Eventually that same day I did it, and everyone ended up clapping. They weren't being jerks about it, they were with me for the journey and had seen me fail and fail, but my persistence to see the task through was inspiring, no matter how trivial the task was in the first place.

"Victory belongs to the persevering." -Napoleon Bonaparte

Later in life, I decided I wanted to challenge my fear of heights, so I started to get into rock climbing. I'm sure there's a local climbing gym near you somewhere where they provide top-roping. This would be a great option for you to get over your fear of heights, or at least to marginally disrupt it!