Staying warm during second swim of F1 race

I am doing and F1 race where you swim, bike, run, swim, bike, run.

Water temp looks like it could be as low as in the low 50s.

I will wear a wetsuit during the first swim and looking for suggestions for the second swim to keep warm. Anyone with experience on this?

Also anyone wear a swim swift suit like the De Soto foil under their wetsuit?

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