I agree, just grit your teeth and bare it. And you'll be underwater most of the time.?
A few years back we had to do similar. Three girls and three boys per session. I had some puppy fat at the time (looking back that's all it was) so was horrified to find the other two guys were the slimmest in the year! I also wasn't too pleased to have to reveal my outie tummy button (turns out all three of us guys had outies, though I was probably the only one who noticed).
We did it, the girls giggled a lot, it was embarrassing. But I'm still here. And now I'm a bit older I'm less self conscious. Probably not the answer you want, but the point is everyone will feel self conscious. Someone will tease others. Then it's over.