Another idea to help supplement the pasture is temporary fencing. Maybe the other person wouldn't mind seeing the horse in the yard a couple times a week for 2 hours or so. Make sure it is supervised time and that the lawn isn't treated with any fertilizer or pesticides.
Electric fencing is simple to install /dismantle. If you go electric, Buy the best charger you can find. Cheap chargers are not worth the hassles (I know this first hand.) The ground system is your friend, set it up correctly and it'll save a lot of headache LOL. I know folks do the double strand electric, but if it is perimeter fencing, please DON'T. Research,call the county extension agent, consult a pro, but don't do the double strand only.
I'd go with a hot wire 4 inches inside or above the cap board in the style the picture shows. Livestock can and will lean and stretchon the top of fencing. They can pop those boards off in no time.
If you go electric, livestock learns to respect it quickly. It's economical, looks awesome when it is installed correctly, and lasts a long time. You can also get the high visibility rope type, instead of wire. I keep hearing that it is also safer, no wire cuts to worry about. Plus the temporary can be jumped off the pasture in several different spots quite easily, if it is set up for it to start with.
I didn't see any specs for emergency/security lighting. Having a barn without electricity, at the moment, stinks! You never know when you will need the emergency lighting. It's something to think about anyways. :)
"Light travels faster than sound. That's why some people appear bright until you hear them speak."
Larry the Cable Guy