[Libguestfs] Mounting disk images with ext2 filesystems on RHEL7

Hope someone can point me in the right direction. I don't know if what I am trying to do should work or not. I have 2 disk images. One is a VM with an ext2 boot filesystem and ext4 filesystems with the OS loaded. I am amble to guestmount this with no issue and am able to see the files that are on the ext2 file system. I can also run guestfish on the image, mount the ext2 filesystem, and list the files. However, the second image I have is only a boot disk image with just an ext2 filesystem. guestmount complains that there is no OS and won't mount. guestfish complains "...wrong fs type, bad option, bad superblock...". Should I be able to mount a boot disk image with guestmount? I suspect I'll have to use the -m (mount) option and not -i (as I did for the image with an OS), but that failed too even though I passed in the fs type of ext2, Why would I be able to mount, via guestfish, the ext2 in the first image (with other filesystems of type ext4) but not the disk image with only an ext2 filesystem? TIA! Lenny B.