I'm all for scripting automatic features based on JA, weather, what gear I'm weariong etc, but sometimes it's helpful to be able to call up a certain gear set whenever I feel like it based only on my input.
You can make a set for cover and then in the init.txt file for Windower, bind the set to a key combo.
bind %!o sc set Cover
Now whenever you press alt + O you will put on your "Cover" set. I know you want to do something automatic here, but this is a nice way to have 100% access to a gear set whenever you want it very quickly and accurately.
I use this for set's that I want access to at random times of my choosing. For instance, for my ninja I bind a macro for the speed feet. So whenever I need it, a simple keystroke will switch my feet. This is mostly helpful when I need to kite something while fighting or pulling, but am engaged. Or when it changes from day to night and switch between my day feet and night feet.
Anyways, this is a nice feature. I made a couple macro binds in init.txt with basic names like "Misc", "TP", "Acc". Whenever I work on a different job's spellcast and I need some random, dynamic gear change, I'll name the set one of my bound macro names and be able to switch to it easy.
p.s. Isn't spellcasr dead now? :p