MySql: I don't really know what installer you are using, but a quick peek at the simplest one I could find, seems to indicate that the installation location is defined by INSTALLLOCATION and there is another location called DATALOCATION.
If TARGETDIR or INSTALLDIR did not work (they might), then you could try setting those two location properties as well. Something like this:
msiexec /i MySetup.msi INSTALLLOCATION="D:\MySqlBins" DATALOCATION="D:\MySqlData" /qb
SSD Disk Cleanup Tips: Also want to let you know about this answer which tries to provide a list of ideas for how to deal with very small SSD disks (60GB is a challenge for a developer PC though - sorry to state the obvious): VS 2017 Installation failed.