Try this topic https://ogrforum.ogaugerr.com/...rack-for-outdoor-use
Good sources of information include doing an internet search for O Scale Outdoor Railroad and do the same search on U-Tube. There is a wealth of information out there. Many considerations will be covered.
In Arizona one big consideration is expansion and contraction of the track given our wide variation in temperatures.
Good Luck and let us know your experience.