Apologies for the delay. I was out of the office on vacation and returned yesterday, so I am just getting caught up.
First, if you are comfortable using the standard 3/4-inch-thick tall end panel, you can order the TFE Oversized panel up to 120 inches tall and use it as a single piece.
Here is the link to the oversized tall end panel:
https://www.barkercabinets.com/product-p/tfeoversized.htm
Using the thicker 1.5-inch tall end panels will require a seam somewhere on the refrigerator enclosure, so you will need to decide where you want that seam to be. The 1.5-inch panels are thicker and provide a more substantial appearance, but they are limited to 96 inches in height, as shown on the website.
This means the enclosure would need to be assembled from two pieces. When creating a seam like this, I generally prefer to make it look intentional rather than trying to hide it completely. I would still keep it above eye level, but placing the seam higher than the refrigerator opening may look a little unusual because the seam would appear on the front face where the cabinet doors meet the refrigerator opening.
A better option may be to align the seam with the top of the refrigerator opening and continue it around the side so it appears intentional. In this case, I would make the lower tall end panel the distance from the finished floor to the underside of the wall cabinet above the refrigerator opening.
You could then use brackets or a solid-wood cleat attached to the underside of the wall cabinet and screw into the upper portion of the lower tall end panel to secure everything together.