I have soap dishes in my tank still, I just got them at Walmart. They are holding up well, though my turtle never really took to sleeping on them exactly. He loves to just hang off of the edge, though, so it works well. They are positioned about an inch or two below the water surface. However, I just put in plastic plants and I am amazed that he can lay on top of those (even being 4") and be supported! It's crazy! I figured he'd just sink the plants ...
So you could try plants. Or you could make an eggcrate underwater resting area like BullDog.
