Dual booting will work, but, it will upgrade the boot loader and make other system wide changes.
Quite frankly, if you have no intention of using this installation of Windows 8 long term, I highly recommend you instead look to virtualise Windows 8 for evaluation and test it in a virtualised environment as you should be able to do what you need without making any system changes.
Other than high end graphics, there is very little difference to using it virtually.
Just remember to go full screen otherwise you may have a hard time getting used to the gestures.
If you already have the ISO (from MSDN or Technet) then great. If not, you can get a preview here - http://windows.microsoft.com/en-GB/windows-8/iso After you have this, if you don't currently have any virtual machine software, I recommend you download VMWare Player