Your feedback here in the Community space is appreciated, @ObsessedFab. Let me provide details on credit card processing fees and invoices in QuickBooks Online (QBO).

While adding the CC processing fee at the time of the invoice payment isn't an option, I recommend sending a feature suggestion to our Product Development Team. By doing so, they can evaluate the idea and consider it for future updates. To request, these are the steps:

1. Access your QuickBooks Online company.
2. On the top right corner, click the Gear icon.
3. Select Feedback.
4. Enter a brief description of your suggestion and then click Next to submit feedback.

See this page for more information: How do I submit feedback?

In the meantime, you can utilize a third-party application to achieve this and speed up the invoicing process. I can help you with that, and I recommend visiting our official QuickBooks App Store, or following these steps to find and integrate an app:

1. Access your QuickBooks Online company.
2. On the left navigational bar, go to the Apps tab.
3. In the Search bar, enter a keyword related to the feature you want to use.
4. Select an app and click the Get app now button when you're ready.

See the image below for visual reference.

Additionally, here's a useful article on how to create personalized sales forms in QBO: Customize invoices, estimates, and sales receipts in QuickBooks Online.

Feel free to use the comment section if you need any assistance. Keep safe.