Possible prefixed layout solution

CustomView.php

<?php
namespace App\View;

use Cake\View\View;

class CustomView extends View {

	/**
	 * Returns layout filename for this template as a string.
	 *
	 * @param string $name The name of the layout to find.
	 * @return string Filename for layout file (.ctp).
	 * @throws \Cake\View\Error\MissingLayoutException when a layout cannot be located
	 */
		protected function _getLayoutFileName($name = null) {
			if ($name === null) {
				$name = $this->layout;
			}
			$subDir = null;

			if ($this->layoutPath !== null) {
				$subDir = $this->layoutPath . DS;
			}
			list($plugin, $name) = $this->pluginSplit($name);
			$paths = $this->_paths($plugin);

			//prefixed Layout lookup
			if(isset($this->request->params['prefix']))
				$files[] = ucfirst($this->request->params['prefix']).DS.'Layout' . DS . $subDir . $name;
			//fallback for standard Layout or just use it if prefix is not set
			$files[] = 'Layout' . DS . $subDir . $name;
			foreach ($files as $file){
				foreach ($paths as $path) {
					if (file_exists($path . $file . $this->_ext)) {
						return $path . $file . $this->_ext;
					}
				}
			}
			throw new Error\MissingLayoutException(array('file' => $file . $this->_ext));
		}

}