Using the backup interface command makes it more complex than it needs to be. You should get very satisfactory backup routing by configuring a second static route with the higher Administrative Distance (like your second option).
one of things I like to do is use equal wieght static routes. This will allow for load sharing and if one goes down the other will still be active. If you only want to use one line at a time use the ip route statement with the weight.
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...