Hi!
I'd avoid using water in the pan as this will fight against the Smartfire - even an empty pan with foil over it will work better.
Top vent may need to be closed a little, see how you get on.
Otherwise you sound good to go! I've got a quick question, what size is the vent on the callow? - I want to make sure our adapters have a reliable list of compatible smokers on the website.