I was able to install OpenBSD with a custom IMG, however, creating a clone from a snapshot failed
Since the OpenBSD project provided an IMG file of version 6,8 I was able to create a droplet from a custom image. As I wanted to deploy a fleet of droplets but did not want to go thru the installation scripts one at a time I thought to use snapshots to create the +1 droplets. However, when booting the +1 the startup seemed to hang access the boot disks.
FYI when doing the initial installation OpenBSD identified 2 drives sd1 and sd2. I did the install on sd1. And when the installer wanted to reformat the entire drive with it’s own scheme I said OK.