You can do that no issue.
The only thing is that you will need to manually unregister / register VMs from the datastore on the esxi host if you want to move the VM to the other host, and things like vMotion etc. won't be available.
But VMFS is a cluster file system, doesn't need vCenter to works. Once the LUN is formatted as VMFS, the created datastore would be visible from both hosts.
Jonathan P.