Why do you want a separate whirlpool vessel with such a small system? It's just more time for pumping it over to that vessel. Also more money for the parts and such for that vessel.
Usually in bigger production breweries that brew around the clock do they use separate whirlpool vessels.
I design small ~60L pilot brewing systems. The whirlpool is done right in the kettle. The pictures I have are really high quality and are to large to post on the forum. If you have an email address that can accept attachements of 1M or better I would be happy to send you pictures.