Poultry netting is the most secure form of electric fence, but is also the most expensive and requires the most effort to maintain. Multiple strands of metal wire, poly tape, or poly rope are also effective, provided you build it correctly, which means it will need to hug the ground contour, and leave no gaps between the ground and first strand, or between the strands, that a coon, fox or other varmint could manage to crawl under or through without making contact with a hot wire. Make that a really hot wire. 7,000 volts plus shock experience. Once trained, most varmints are reluctant to try again.
The maintenance factor between netting and alternatives is evened out if you are willing to use Roundup of some such chemical to kill all the plants that will grow up into it to ground it / short it out. Othewise, you have to take it down or move it to mow under it. Worse luck, closely cropped grass grows faster than tall grass does, so this means you have to mow often to keep the area clear.
Or, you could use something else, like a strip of black plastic or heavy landscape cloth to physically smother out any vegetation under the fence. Yet another option for this is paper feed sacks or even newspapers. Use a mower to scalp the grass down to nearly bare dirt and lay your faux mulch on that. Some of that depends on how large an area you want to build. Either way, plan on keeping wide swathes mowed on either side to create a visual opening adjacent to the fence. Each side of the fence kept clear at least as wide as the fence is tall.
As for trees and coons, they can easily use a the tree canopy as a highway to cross over any fence. Or a tree to shed or building. Don't know if they would jump from a tree branch several feet to the ground, but with coons, you never know.