Super easy. The rear shocks are simply unbolt, remove, replace, re-install bolts. Most shocks should come with a strap keeping them compressed to ride height. Don't remove the straps until they are bolted it.
I left my front tires on my Ranger when I replaced the shocks and didn't find it hard at all. I did pull the rubber guard out of the fender to get to the top bolt, but that was it.