the only way i think you will survive in the atlantic with a spring suit is if your skin is as thick as a seals and you got tons of adipose tissue as insulation buddy
i dont think a spring suit is a good idea,especially in a comp
BUT its your choice.
I once went in at the hoek in boardshorts and rash vest,waves were good,stayed in for 3 hrs,but it was the biggest mistake of my life.
I wish you luck