Doh. Your post got caught in our spam filter. Sorry for the delay. I hope your race went well.
For future reference, is you have a recent event for comparison, that will produce a much more reliable estimate than other methods. On that note, how did your GT time compare to your Gothic time?
The one thing that I would (have) caution against is so many events so close together. No real fitness will be gained within a month of an event, so adding additional races will likely worsen performance. The exception is if you use the middle race (Power of Four in this case) as “research” and intentionally go slower than you can. For that to work, you need to make sure your partner is on the same page.
Hopefully that helps for next year!