Sure
So you use IIS to set up a pretend webpage. In IIS you can add directories. I added the folder that contained the files. The new files goes from your standard file path to looking like this;
http://localhost:8040/Heritage/filename.jpg
So it looks like a webpage, but it is hosted locally (port 8040), the directory is called "Heritage" and the file is at the end.
I didn't have to move any files and adding this file path to the table means you can call it up in the HTML to display in the sidebar. To add more images for different tables or columns from another location I just add another directory to the existing "web page" that points to another folder.
(So it would be http://localhost:8040/Bridges/filename.jpg)
The biggest challenge was getting the program permissions to access files on different servers. I had to leave that part up to IT to figure out.
Here's the html for calling the column the image file path is in, and setting a default size;
<li class="customCalloutData" style="margin-top: 10px;font-size: 14px">
<img src="{{feature.Photo1.value}}" width="500" height="377">
</li>
And yes, "Photo1" is the name of the column the file paths live in