I would suggest a series of smaller array objects
or 3x3 minimum. Where each one represents a set size of 1000px by 1000px(or whatever you want really, just a hypothetical suggestion)
when creating your map pin all the objects(blocks?) of one array to a single object.
When a player moves to to a new araay, destroy the farthest, move the array over and create a new piece of the map.
I would also suggest moving 9 map pieces rather than the player. That way your layout is of a set size. Alternativly you can just move the player and the map once the player reaches a certain section of the map thus reducing map movement to a minimum.
Or don't use an array at all and just create and pin the objects straight to a HUB object as above.