Ubuntu – install another linux os without bootloader

From my experience you should install the bootloader in the hard drive itself instead of a partition, most likely /dev/sda (unless you are using a mac with OSX where you need to install EFI in the hard drive and create a partition for the bootloader).

Every time you add a new distro grub checks for installed OSs in each partition and it will update your grub screen with an option for each OS.

The only thing that will happen is that some distros have a different look and feel for grub so it might not be as nice depending on what partition you install last.

Finally if you want to update your grub (because you broke it or don't like the looks of it) you can put a live cd (or usb or whatever you fancy) and fix it. There are some guides for it. My point there is that you can play around without actually losing information though backups are always in place ;)

This is relatively simple. Following @hmayag advice will insure you don't accidentally overwrite the MBR on your Windows 8 drive. Install Ubuntu to your SSD and install grub to the MBR of the SSD. You will end up with 2 bootable systems after reinstalling your Windows 8 drive. (Both drives will have an active MBR) You can choose which to boot from through the BIOS, but I would set the boot order to the SSD as the first drive and reinstall grub2 as outlined here so that you can choose either system at boot time without adjusting boot order in the BIOS.

You can do this by making the right choices during installation as well and skip removing the Windows 8 drive but be absolutely certain that you install grub to the other drive (the "fresh SSD")