OperaSetup.exe --silent "--installfolder=F:\Softwares\Opera" --pintotaskbar=1 --singleprofile=1 --setdefaultbrowser=1 --launchbrowser=1

That should silently install Opera to f:\softwares\opera where all of the profile files are in f:\softwares\opera\profile while setting that Opera as the default browser for the current user.

Hopefully that will avoid the space issue on your C drive. Note though that with the default installer, it'll have to fetch the setup files from the net, so be patient if on a slow connection and wait for Opera to pop up after a bit.

set APPDATA=F:\Softwares\AppData\Roaming
set LOCALAPPDATA=F:\Softwares\AppData\Local
set ProgramFiles=F:\Softwares
set ProgramFiles(x86)=F:\Softwares
set ProgramW6432=F:\Softwares
set USERPROFILE=F:\Softwares
set HOMEDRIVE=F:
set HOMEPATH=F:\Softwares
set SystemDrive=F:
set TEMP=F:\Temp
opera_installer_name.exe

However, if you do that, if the paths to the profile aren't hardcoded in some file that the Opera exe uses, you'd have to always start Opera with a batch file like this:

set APPDATA=F:\Softwares\AppData\Roaming
set LOCALAPPDATA=F:\Softwares\AppData\Local
set ProgramFiles=F:\Softwares
set ProgramFiles(x86)=F:\Softwares
set ProgramW6432=F:\Softwares
set USERPROFILE=F:\Softwares
set HOMEDRIVE=F:
set HOMEPATH=F:\Softwares
set SystemDrive=F:
set TEMP=F:\Temp
launcher.exe

This is untested though.

The only reason to even try this way instead of the standalone installation is if you want to set Opera as the default browser on that drive. Note though that even with this method, Opera will write to the registry and the registry file(s) are on your C drive.

Or, for launching launcher.exe after Opera is installed, you might be able to use these command-line switches so that Opera doesn't use appdata on your C drive. This may be an alternative to the batch file.

https://peter.sh/experiments/chromium-command-line-switches/#profile-directory

https://peter.sh/experiments/chromium-command-line-switches/#user-data-dir

Or, you could use the command-line switches for the installer to see if you can get around this issue. There's a recent thread for it. Maybe someone can post a link. Again though, you'd only need this if you want to make Opera's launcher.exe the default. But, you still might (don't know how the installer sets things up. It might hard code the paths in a file by launcher.exe or something) have to use the user data directory command-line option in an Opera shortcut. Or, you'd have to modify the paths in the registry for Opera.

Again though, the standalone installation would be so much simpler.