This entire level is just one screen. Not pictured here are Batman, Killer Moth, or the lifebar.
The ground stamp is the same as before, except with the addition of the color green. So, this is the ground for level 1-3:
However, one important thing to consider is that this level is too big to fit in Mario Paint. This picture shows the absolute full capacity of a Mario Paint drawing:
Take a look at that picture when it overlaps level 1-3:
So, in other words, some cropping and trimming is necessary. Here's level 1-3 with a small amount of the image sacrificed:
This doesn't leave as much as one pixel to spare, but, rest assured, THIS IS POSSIBLE to create in Mario Paint.