I think you want to add BACKUP DB in here and BACKUP VOLHISTORY and
DEVCONFIG.  I like to do it after step 2 in your scenario.  If you do not
have a flat file copy of the VOLHISTORY and a backup of your DB you have no
way to recover.

Reclamation of an offsite volume looks similar to a move data command of an
offsite volume:

tsm: TSMPRD00>q pro

 Process Process Description  Status
  Number
-------- --------------------
-------------------------------------------------
-------------------------------------------------
     100 Move Data            Offsite Volume 422059 (storage pool
     100 Move Data            Offsite Volume 422059 (storage pool
                               CPY_OFF_POOL), Target Pool CPY_OFF_POOL,
Moved
                               Files: 76648, Moved Bytes: 26,811,502,169,
                               Unreadable Files: 0, Unreadable Bytes: 0.
                               Current Physical File (bytes): 673

                               Waiting for mount of input volume 420773 (43
                               seconds).

                               Current output volume: 422542.

Volume 420773 is one of the volumes in what you call the onsite tape pool.
The proper name for the onsite tape pool is the PRIMARY POOL.  You can also
have data from a primary pool copied to more than one COPY POOL.  I have an
onsite COPY POOL and an OFFSITE COPY pool because I cannot afford exposing
my OFFSITE copy to being lost in a disaster because I had to bring it back
to recover a failed PRIMARY POOL volume.

Hope this helps.