Consider the following.
[member="Kalis Affassa"]
I think your three biggest problem isn't protecting from ground attacks since we have shields. And something this big would have good ones. But as [member="Valiens Nantaris"] pointed out, mobility issues.
Maintenance problems. Can you imagine the monumental undertaking it would be to install or repair those tracks. I've done a track installation on a
Snowcat, which arn't very big nor heavy compared to a tanks, but it's not a cake walk. But this is just obscene. You'd need something that could pull hundreds of thousands (millions?) of tons of track up into place, then somehow pin the tracks together. What I'm getting at is maintenance work would be extreme on its very large pieces. And the constant fixes and preventative maintenance on everything else.
Cost. Lets face it, this thing is a kitchen sink on treads cause you're just gonna be throwing credits down it. Maintenance, fuel, personnel, consumables. Whatever else this thing will use. All for sitting on a world cause its certainly to heavy to lift off world. No one would ever dare attack it upfront. It may be a giant mobile fortress but where's it gonna run to when a fleet starts bombarding it? A waste of a billion credits when they slag it.
I don't wanna knock you from trying. But something this large, technical, and expensive would only be feasible by the largest companies with serious major faction backing to make and maintain it. Your better off buying Star Destroyers for 150-200 million credits a pop with more firepower and maneuverability.
The Purple People also wouldn't like it without serious dev threads.
In conclusion. To answer your question. Yes, it is possible to build something this large. Is it feasible, not in the slightest. It's got superweapon syndrome all over it and some former dirt farming, backwater world, Jedi terrorist would blow it up with a glow stick and some grenades. Or aforementioned fleeter.