Here let me make a clarification.

I have no issues with the tank, if we can make it reasonable.
The issues I'm encountering is that, no matter WHERE the tank is from... a 'goodly' survivor stronghold, Eden, whatever.
The MOMENT that it comes down to just the tank and its driver on their own out there, it's a HUGE target... for every sizeable group of outlaws and the Miraculum. Anyone who thinks they have the numbers to take it will want it; something like that is a huge boon. ESPECIALLY for those who aren't magically inclined. And for those who are magically inclined, such as the Miraculum... they'd take it just because they can. To keep it out of enemy hands, to employ it strategically as they see fit, etc. So it would need to travel with a big enough group to defend it. As long as that is met, we can work anything out.