QBO has some wonderful programming behind the scenes of this software. BUT to say this can not be done is just BU!!S!T. You simply need to copy the code that allows the customization of the sales templates and point the code the table and columns for the expenses. From there, the default template needs to be loaded in a report writer mode which has already been written.

I understand that this is an 'enhancement' but how many customers will you loose by not spending the 20-40 hours of work including QA? 

Be consistent and allow your clients to run their business in a way that is correct grammar and tailored to their industry!

More than happy to speak to a developer or programmer about the approach to take as I used to be a programmer and now a bookkeeper