I go a different route. I like to research the subjects of the cover and create pages including any info I can find about them. Of course I also have info about the stamps, cancels etc.
The simpler covers are usually mounted two a page but more in depth pages will include the information found and any other pertinent images, either scans of the back of the cover, contents or pictures of the subject, if I can find them.
I print them on acid free cover stock and mount with clear acid free photo mounts.
Here's an example of an 1855 stampless cover. The recipient was an inn owner just east of Toronto. His inn is now a museum.

As I've said many times, Google is one of my favourite stamp collecting tools.