Registered last night as well, hopefully this thing will happen next year.
I also got my coin at the 2019 rattler. I had to contact them via email to get my corral position since the race was cut short. My finish time was 3:57 and they gave me purple corral. They are notorious for stingy corral placement at the rattler and they still need to work out the right cutoffs for the new course. The corral times on their website are for the entire course and are just silly. 4:30 for red would translate to 1:30 lap times. Only the top 3 finishers (pros) were barely at that pace for 2 laps and it’s likely they would have finished 3 laps slower than 4:30. So, nobody would have gotten better than green corral for that race if they didn’t adjust it. They need to add 60-90 minutes to all the corral times to make them reasonable unless they make the course much faster.
I ended up doing the stage race last year (8:05 finish) and improved to green corral and just 5 minutes off red. It’s a better course for me compared to rattler, but my fitness was similar and it just shows how silly the Austin corral times are. I’m still planning to do the rattler in a couple weeks, but I’m not expecting to improve on my green corral.