I know these are expensive now but I don't understand why more people don't use them. I have had one for years and use it any time it's over 95°. Many times I'm sitting in my car suited with this on and everyone else is sweating their butt of waiting to run. I won't even be sweating.
I put 3 4x6 freezer packs and a couple handfuls of ice in the water for a run. It will last you a good 10 minutes once you start the water running. If you are adding weight anyway this would be better to have than lead.
https://coolshirt.com/product/drag-pack/
^^^