Don't totally change your game because it works very well most of the time. No one style is perfect, so I'm not sure what you are looking for besides success at ABC Nationals.
I just think you might try a couple different layouts that you would normally not use. What works on the THS for you causes you problems on the ABC shot. Try something different. With the limited amount of time on the lanes, it is hard to try a bunch of different alternatives without running out of frames. It sounds like you were able to find a line to the pocket, so you played it safe instead of going for the gold by trying a different ball or release to improve your carry. That's likely what most of us would do.
If any one of your right handed teammates had any success at all, I would venture you should be able to find something also. Your shotmaking skills may be physically limited, as you say, but are more than adequate to score with.
As you say, we only see this type of difficult shot a couple times a year. Everything else is a version of a THS that can be manipulated with minimal efforts. Judging by the scores from the locals that went, it sounds like I need to find a tougher place to practice.