I have a privacy fence thats pictured below surrounding my entire backyard. it would be hard for a raccoon to climb but I guess they could borrow under. I have dogs Loose in the backyard 6 times a day and night minimum that scare most critters away. I want to build an enclosure among some palm trees out there with 2' walls(made of logs like this person did) for my 8-9"(4lb)Burmese Black Mountain tortoises. Do I NEED to cover it? I will be planting other things in there for them to hide under but....I want it to look natural and be safe.