as someone who looked into this in the UK (eternal rain), i experimented with a small basic circle track. i will say IT DOES WORK but take into consideration the massive amount of maintenance. clean the track often using wet and dry but even then the connection isnt great. dont fasten the tracks together too tightly to avoid buckling on hot days, i did not experiment with points but i imagine they will need a lot of attention to stay functioning. creatures will make a home out of anything they can get inside so be weary about tunnels and sheds. last and most obviously, keep the power supply dry. so overall, it can be done but is high maintenance. i never went through with it since i decided to do some DIY on the loft instead but i know an outdoor layout is tough for OO. maybe scale up to make life easier. but best of luck.