dd if=/dev/zero of=mountedImage.img bs=512 count=131072
fdisk mountedImage.img
    n
    p
    2048
    131072

losetup /dev/loop1 mountedImage.img
mkfs -t vfat /dev/loop1

cat /sys/module/loop/parameters/max_part

modprobe -r loop # unload the module
modprobe loop max_part=31

options loop max_part=31

truncate -s64M file # no need to fill it with zeros, just make it sparse
fdisk file # create partitions
losetup /dev/loop0 file
mkfs.vfat /dev/loop0p1 # for the first partition.
mount /dev/loop0p1 /mnt/

losetup -P -f --show my.img

$ los my.img
/dev/loop0
/mnt/loop0p1
/mnt/loop0p2

$ ls /mnt/loop0p1
/whatever
/files
/youhave
/there

$ sudo losetup -l
NAME       SIZELIMIT OFFSET AUTOCLEAR RO BACK-FILE                                                                                      DIO
/dev/loop1         0      0         0  0 /full/path/to/my.img

$ # Cleanup.
$ losd 0
$ ls /mnt/loop0p1
$ ls /dev | grep loop0
loop0

los() (
  img="$1"
  dev="$(sudo losetup --show -f -P "$img")"
  echo "$dev"
  for part in "$dev"?*; do
    if [ "$part" = "${dev}p*" ]; then
      part="${dev}"
    fi
    dst="/mnt/$(basename "$part")"
    echo "$dst"
    sudo mkdir -p "$dst"
    sudo mount "$part" "$dst"
  done
)
losd() (
  dev="/dev/loop$1"
  for part in "$dev"?*; do
    if [ "$part" = "${dev}p*" ]; then
      part="${dev}"
    fi
    dst="/mnt/$(basename "$part")"
    sudo umount "$dst"
  done
  sudo losetup -d "$dev"
)

sudo apt-get install kpartx
losetup -fs my.raw
sudo kpartx -a my.img
ls /dev/mapper

/dev/mapper/loop0
/dev/mapper/loop0p1

mkdir -p d
sudo mount /dev/mapper/loop0p1 d