Hello there, @aleck.
Thank you for visiting us here today. Allow me to step in and share some insights about customizing and printing the Packing Slip under the Order Fulfillment feature.
Currently, the option to customize transaction templates is only for the invoice, credit memo, sales receipt, purchase order, statement, estimate, sales order, and build assembly. However, I know some applications you can integrate with QuickBooks for customizing your Packing Slips to include the items and tax code line.
You can visit our MarketPlace website. You can scan through the site to get a better comparison of the available apps and see if one meets your needs.
While doing that, I'll be sending feedback on your behalf. I appreciate you for voicing out your idea, with that we can then address what needs to be improved to give our customers a better customer service experience.
That should get you going today, aleck.
Keep me posted if there's anything else I can do for you. Just add a comment below or mention my name. Wishing you all the best!