Very nice, most monsters with this level of fat are walking buffets (looking at you, Popo). A while ago I had an idea for a Gravios sized "cave wyvern" that had a tail that was a fat reserve, similar to a Gila monster.
Plotted out a little bit of its appearance. Its body structure is similar to Gravios, it has rubbery, Gypceros like skin. It has the head and neck of Khezu, Chameleos like spikes and tail. It normally walks on its hind legs,but drops down on all fours when running.
Named Dyzola, it is too big to climb cave walls, instead it tunnels into them and covers itself in ice to hide and ambush prey. That being said, where Khezu and Gigginox attacked with electricity and poison, Dyzola attacks with ice. I also imagine Dyzola laying its eggs in hot springs.
Hmmm, that sounds really nice, but I would suggest obtaining inspiration from other animals to avoid making an “MH chimera”. I get were your coming from, but it could help your wyvern develop a bit more of it’s own personality with a few more biological differences added.