WingedCat said:
Trust me, I am aware of the "how could such a creature exist" concerns, and the JTAS article addresses them.

(Not every detail - I don't have pages and pages for this - but at least a paragraph.)
That said, I draw your attention to this from the first post.
WingedCat said:
"How can such a large creature exist" is off-topic for this thread: this is also setting up how a robot this large, or any other non-ship/vehicle this large, would be reflected in game mechanics
I invite the mods to delete any further comments in this thread about "how could this creature exist", that do not mention game mechanics. The need is for game mechanics that work for creatures, robots, and any other such thing of this size, regardless of how it came to be. Debates on how the creature could exist are likely to bury and/or prevent discussion about game mechanics.
So, if you really must discuss the creature itself, please make or find a separate thread. Please do not discuss that here.
You came seeking input. You don't get to control said input. Take what you get or don't ask the question. If you think off-topic comments, or worse, comments that YOU don't personally believe are appropriate belong on this thread then I suggest you get off the internet altogether. Your request is insulting to everyone and unrealistic.
You've received a number of inputs. Based upon your response I would hazard a guess that you have yet to hear what you want to hear. Someone asking "how could such a creature exist" is entirely valid. You postulate a creature that nature says shouldn't be able to exist in the first place. If you simply want handwavium to justify it's existence why pose the question in the first place?
A creature of that size has formidable energy requirements that must be met. Meeting it's energy requirements has linkage to size, to locomotion, to everything about it. And knowing HOW it works is a predecessor to providing you game mechanics on how to implement it. Based on your proposed mass (100,000 tons), it's got to be gigantic. This means a gigantic circulatory system with multiple organs, perhaps even multiple brains. Do you think such a thing is germane to your question about game mechanics? I would say yes because defining the creature itself means you answer the questions you seek.
To distribute such weight you'd want to spread the mass around, so it could take on a centipede-style shape rather than a larger four-footed animal that would be bearing 25,000 tons per leg if it was four-footed. Having many multiple legs to move it's mass is similar to how technology today transports heavy items while distributing the weight along multiple axles and wheels. Distributing mass is a game mechanic.
You'd also have to determine just how it would move crashed spaceships (you didn't provide a size, but if they are 'crashed' then probably no larger than 1,000 tons displacement. Which relates to skeletal structure to spread the load along the body (as well as how it's made up, which relates to how much damage it might take). Does it engulf the space ship somehow? Roll over it? Dig underneath it? Wait patiently while a crane(s) lift the cargo onboard? Are there tentacles that can act as loading, or perhaps straps while it's loaded?
All of the above questions are just as germane to your animal as they would be to a robot, mechanical transporter, or even a grav-based vehicle. The game mechanics would come down to how much it can transport, how much damage it can take, how much energy is required, and how you control it. As an NPC or mechanism much can be handwaved (going into detail of how gunpowder is detonated doesn't do much for RPG shooting of a gun... pew-pew-pew! taking three rounds of ammunition doing 1D6-2 is sufficient to describe the Marduk Arms TL-6 auto-pistol that your character is being shot with).
Some inspiration on transporting large objects - https://www.dailymail.co.uk/travel/travel_news/article-4540604/The-biggest-things-moved-road-revealed.html - perhaps one or more of these images will help with your article.