Same rule here in Iceland.
I just wear my trunks while walking 'round the locker room before swimming and pick a shower that I can face the wall comfortably in and wash with 'em on and if the shower guard talks to me I just say "yep, I will, no worries" and I do.. I do wash without the trunks on, I wait until I have a chance to do so "alone" (obviously, I don't go when it's crowded, drop drawers a little, and wash, then pull 'em back up!
After the pool, I do pretty much the same thing, then hop off to the bathroom so I can take 'em off properly, squeeze the water out of 'em, and dry off a little. Then the towel takes their place.
Is a bit stressful cause I'm still getting used to it and all, but no-one's given me any trouble.