Recently I uploaded my new QGIS plugin ‘QuickCRS’ as experimental to the official QGIS Python Plugins Repository. If you check the option “Show also experimental plugins” in Plugins|Settings, you can install the latest version directly from within QGIS 2.x. I’m still working on a port for QGIS 3.x.
‘QuickCRS’ is a very simple QGIS plugin. It allows you to set the Project CRS and enable On-The-Fly Reprojection (OTF) with just a click of a button. The first time you use the plugin, you have to set your favorite CRS. After you’ve done that, simply click the QuickCRS button to set the Project CRS and enable OTF. If you want to change your favorite CRS, this setting can be found in the Menu Plugins|QuickCRS|Settings for QuickCRS.
The issue that was reported concerning installation of ‘QuickCRS’ in QGIS for Mac, was resolved in version 0.3.4. ‘QuickCRS’ now works on Windows, Linux and Mac.