Is nomodeset still required?

You should use the parameter nouveau.modeset=0 instead of nomodeset.
Install the Ubuntu system and the proprietary NVIDIA drivers in this way :

Boot from the Ubuntu DVD/USB installation media you had created before.

Highlight the option 'Try Ubuntu without installing' and press the E key.
Add nouveau.modeset=0 to the end of the linux line - press F10 to boot.

Install the Ubuntu operating system - when finished reboot the computer.

Highlight the Ubuntu entry in the GRUB boot menu and press the E key.
Add nouveau.modeset=0 to the end of the linux line - press F10 to boot.

On the login screen press Ctrl+Alt+F1
Enter user name and password - execute :

sudo apt-get update
sudo apt-get install nvidia-352
sudo reboot  

Generally it is recommended to use the NVIDIA drivers from the official Ubuntu repositories.
But as you have very new graphics hardware, you can install the latest official NVIDIA drivers.
The xorg-edgers PPA does not provide the drivers anymore and was replaced by GPU Drivers.

sudo add-apt-repository ppa:graphics-drivers/ppa
sudo apt-get update
sudo apt-get install nvidia-361
sudo reboot  

After the installation adding the parameter nouveau.modeset=0 is not necessary anymore.

I had the same problem with my Xubuntu 18.04 version that runs on Nvidia GPU. I tried to installed the latest Nvidia-390 and nvidia-prime drivers and updated my driver installs as these solutions show [1] [2], and I added nouveau to the block list, but none of these worked. So what I did is that I added the parameternouveau.modeset=0 to grub.cfg file in \boot\grub\ directory. I added the line after every "linux..." line, for instance:

menuentry 'FAILSAFE' --class ubuntu --class gnu-linux --class gnu --class os {
    recordfail
    set gfxpayload=$linux_gfx_mode
    insmod part_msdos
    insmod ext2
    set root='(hd0,msdos8)'
    search --no-floppy --fs-uuid --set=root 36286167-4eba-4a1e-a202-155c6baafa01
    linux /boot/vmlinuz-2.6.37-12-generic root=UUID=36286167-4eba-4a1e-a202-155c6baafa01 ro vt.handoff=7 quiet splash nouveau.modeset=0
    initrd /boot/initrd.img-2.6.37-12-generic
    } 

So, I believe you have to add this parameter in all the script. I tried this solution and Nvidia GPU driver stopped crashing.

Another approach as described here

Execute sudo nano /etc/default/grub and add the parameter nvidia-drm.modeset=1 to the line GRUB_CMDLINE_LINUX_DEFAULT. Save the change you've made and run sudo update-grub.
Restart the Ubuntu operating system, and now, everything should work properly - right as expected.