Not hard, if you don't mind doing it every time you used the tool. Spray painting only holds up untill you use whatever you painted then it needs to be done again.
Ok, this is exactly HOW I keep my axes. Though to be honest, I just use inexpensive grey primer. As long as the head is completely painted, I KNOW it's sharp and ready to use. Once I use them, FIRST I clean them, then I sharpen them (yes, even the shovels), then I repaint them.
It keeps them ready to use and keeps the rust to a minimum. I know, I know, I'm somewhat odd.
At least I don't paint the wood handles an odd color like my grandfather did. He came across ten gallons of pink paint that he kept in his 'work shed' that held his work bench where he sharpened and repainted the metal in grey primer and the wood.
He painted that shed and ALL his wood handled tools PINK. Trust me. You borrowed any tool from my grandfather. YOU BROUGHT IT BACK as soon as you were done.
Would YOU want a pink shovel in YOUR garage?