Maybe place the creature in at least two places. One is the nipple that is variable and one is somewhere the creature stabilizes most of the weight then you have the upper/lower torso or the neck of the creature that has been morphed in some way.
After placing the creature, you should be able to animate sections of it, because they are static in relation to something and you have no clipping if you know the min/max values.
Sadly, I have no practice with animating and what tools to use. Or how much work it needs.