Can I use a large external hard drive both as installation media and backup drive?

I am planning to upgrade my Mid 2010 13" Macbook Pro to Yosemite from Snow Leopard, on a new SSD hard drive.

Being more experienced now with UNIX/Mac, I want to have a clean install to get rid of the beginner cruft I had built up. My idea of a backup is simply a basic copy/paste of my Home folder (about 130GB). Here's my plan:

1. Using Disk Utility, partition my new 500GB external hard drive into two parts. One for my Home folder backup, and the other for the installation media.


2. Copy my Home folder to the backup partition on the external hard drive.


3. Use createinstallmedia on the other partition. Tutorial here.


4. Install my new SSD.


5. Plug in my external hard drive. Hold down Option key when turning on the computer, and proceed from there.

Does that sound like a good plan? My apprehension is that the two-partition setup on my external hard drive might corrupt my backup data, given that I also set it up as a bootable installer media.