Looks like a fun project 🙂
If you're quite far away you might get benefit out of just converting the frog to a single tissue and goaling to the current skin.
If you're looking to learn more thoroughly though, seeking out frog anatomy reference and building out an anatomical rig, even if it's kind of basic would be pretty beneficial, and rewarding!
Will give you the flexibility to push in closer with the camera with confidence of getting nice organic looking results too!
If you're not too concerned about fat, you could convert the skin mesh to a tissue (without filling the interiror with tets) and have it slide around on the muscle bake. Would still look pretty cool.