No answer to your question, but would love to hear the story of how you qualified, and perhaps a race report afterwards?

Sure, I have a blog. I can share after the event,

I have done the race twice. Water temps will be lower 60s to upper 50s. If you've done other races, and I assume you have, the temps should be comparable.

It's an amazing race. Have fun .

I live in Stockholm and have been swimming and swimrunning this whole summer. It has been a mild summer and I would guess that temperatures would be between 14C - 19C, you can manage with your current swimrun suit, if you prefer more comfort maybe wearing a swimrun vest underneath.
Weather forecast for the next 10 days looks solid (between 13C - 20C) and not too rainy or cold so it won't be the worst you can face here hehehehe.

Thank you both for your response. Very helpful :)

Interesting...do you find those cold temps to be bothersome and painfully cold in swim run? Normally a full suit would be required for those temps at the lower end in an Ironman, and even then, booties would be allowed & you'd be swimming faster as you don't have shoes.

But in Swim/Run, I heard that you can tolerate the colder temps even more because your body temperature from running is higher. Everyone uses cut off at the knees suits (most do anyhow)...Seems that would be a recipe for cramping and shock to the system.

I did the Stockholm SwimRun in May and temps at the baltic side of the race were around 11C, I can assure you that as your system is warm from the run you can deal with that easily. The painful part is submerging your head on these cold water. It requires some strength to do it. My recommendation to make this more comfortable is to have a neoprene head band that can keep your forehead and ears warm and still let the head ventilate.
As a Brazilian who moved to Sweden I've learned that you need to kinda accept the coldness and relax. The more you focus on how cold is it the more tension you add and the more you cramp while swimming.