Should I use table hints with a process-keyed table?
You said

.. no control over the stored procedures
.. low volume server, e.g. not too many of these batches will be running simultaneously.

Therefore, I'd do nothing. Hints should only be added very judiciously when required. As it stands, you have no known issue to solve.
If you still want to add a hint, then simply use ROWLOCK to disallow table locks.