Flashed my video card with macvidcards.com - No Bootscreen!

[tsialex]

If you don't have a EFI card, you will need to install 10.6 to 10.9 and use it to edit files on the 10.13 disk. You can set boot-args with just Terminal from macOS, no need to enter Recovery. But to disable SIP, you need to boot Recovery from 10.11->.

To do what you want to do without a EFI card will be a hassle.

With 2 drives, one with 10.6 to 10.9 and another with the High Sierra installed by another Mac, you will do it. It’s just a lot of work.

 

[Macschrauber]

You can use command-r for booting into recovery with no boot screen if your gpu is supported by the recovery kexts