Hi, @chris-r-624. I'm here to help.

You are correct. Creating a portable company would only include your financial data, and customizations such as custom templates, logos, and images will be removed. As such, it serves best as a copy for reviewing transactions.

First, if you restore the portable company file and place it back in the original location with the same file name, it will overwrite the original one. It would be advisable to either rename the portable company file or save it to a different folder. If you prefer this method in reducing your company file size, please refer to this guide about restoring missing customized templates, logos and information from a restored backup. Here's how you can restore a portable company file: 

1. Open QuickBooks and log in as an admin.
2. Go to the File menu and select Open or Restore Company.
3. Select Restore a portable file, then select Next.
4. Select your portable company file. It should look like this: [Unique company file name].qbm. Then select Open.
5.  Either rename the portable company file or save it to a different folder.
6. Read the notes on the Where do you want to restore the file page, then select Next.
7. When you're ready to open your file, select Save.

Next, you can also consider condensing your company data file which will retain your customizations and templates while removing transaction details and list entries that may no longer be necessary. However, it's important to note that this may or may not reduce the overall file size. 

Before beginning the condensing process, I recommend reconciling all accounts, printing all reconciliation and discrepancy reports, saving these reports in PDF format, and creating a backup of your company file. It's also a good idea to consult your accountant before proceeding with the condensing process. Here are the steps you can follow to condense your company data file:

1. Select File, then select Utilities.
2. Select Condense Data.
3. Select Keep all transactions, but remove audit trail info to date.
4. Select Next.
5. Let the process complete. Select Close.

Let me add this article as a future reference about the maximum number of list entries you can make in QuickBooks Desktop to help you manage your data: Maximum number of list entries (list limits and custom fields). 

We're always here in the Community should you need further assistance reducing your company file size to improve your software's performance. We'll do our best to assist. Take care.