I believe the destination folder option doesn't appear after running the installer once, it assumes you're just wanting to reinstall the game so it doesn't allow you to choose a different directory. Only solution I know of would be to remove entries from the Windows registry, which I won't go over here.
Instead, if you already have the game installed, you can copy the
C:\Program Files\Rigs of Rods folder to your other drive then run the uninstaller to remove the original files.
Another option is to download the zipped release instead from Itch:
https://rigs-of-rods.itch.io/rigs-of-rods
With this you may have to install the
Visual C++ Redistributable and
DirectX Runtime manually.
Regardless of where the game is installed to, the user folder (
Documents\My Games\Rigs of Rods) remains. This folder contains all mods, which usually ends up taking up much more space than the game itself. There's two ways of moving this folder:
- Create a config folder inside the install directory (see both methods on the General FAQ)
- Set a folder path using the Extra mod path option in Settings -> General. With this the game will load mods from the specified folder.