There is the value "Total Deductions" that can be added.  It appears to be Form 1040, Line 40 (Itemized or Standard Deduction), so it isn't only itemized deductions but it might be a starting point.

To add a column to HomeBase see  https://accountants-community.intuit.com/articles/1607749-customize-and-save-a-homebase-view

You will want to make sure you run HomeBase Tune-Up https://accountants-community.intuit.com/articles/1608793-running-proseries-homebase-tune-up after adding the Column and saving the customized view.