You could set the spoon on top of the container. It would still be conveniently located, but there would be no possibility of it sinking into the sucralose.

You could set the spoon on top of the container. Or, for a slightly more complex solution, you could also make a small paper cone, tape it onto the side of the container, and leave the spoon in that.

Either way, it would still be conveniently located, but there would be no possibility of it sinking into the sucralose.