Most of the posts after yours were more directed at SoCal I believe. As for the tank, I've replaced mine and thankful I don't have any worries about it any longer. When I think of all the things I've changed on mine, the money spend on it originally and to make it what I want.... the coolant tank upgrade was a small amount compared to just the other things found just under my hood. I'm looking at building a gauge pod so that I can monitor water temp/Volts/Oil pressure and I'll have over double the tank upgrade price in that. It's all in what you want and use the SS for. I run mine rather hard at times, and many of those times I'm several hours from home. Peace of mind that I have not used cheap parts that will fail as quickly over time are worth it to me. Being able to monitor what the machine is doing without having to rely on idiot lights is priceless to me.
As for failing tanks, I've seen pictures of ones that split the tank over 1/2 way while out on a trip. Can it be fixed? About any auto parts dealer will have some type of tank you could adapt if only held in place by zip ties. I've done many roadside repairs in my motorcycle/Slingshot history, but the best ones are the ones that preemptive the threat beforehand (in my garage, out of the sun!) in my opinion.
All great advice and thank you to all! I have an appointment at the dealer next Tuesday for them to look at it and decide what the failure is. After they tell me I will make the decision. I paid a good chunk of change for the six-year warranty plan and this is covered. Being stranded sucks and I agree the price of a new tank - replace it and forget it - is very attractive. I will let you know when I know 😎