I will be honest, the last time I had to crawl under my truck and pull down a spare while in the rain, I swore that was the last time, so I cut all the shit out, and tossed the spare in my bed. I run a bed cover though.
The side mount looks nice, email them and see if they will sell the bracket separately. Or go to a big welding company, they should be able to make a bracket. My uncle has a huge machine that he uses to cut out metal etc