Hi,
I'm not sure if you can just put the VSTs in another folder, and then change the path for them in ASCs Preferences. Perhaps it works. You will know when you get updates. Just check the updates is installed the new place then.
You can uninstall the applications And then set a new path for a new install.
FYI - You can't change path for VST3 plugins - only VST2. So be sure you don't use VST3, if you wan't a new location.
Remember to direct your DAW to the new location.
You don't mention the connection you will use for your SSD. Keep in mind that a SSD is'nt faster than the connection you use. It's not allways a joy to use external disks.