We have 2 Dobermans - I use two types of leads
1. I have a cable with a pulley. I use rachet straps connected to trees on either ends and thighten the cable. The webbing on the rachet straps protect the tree so n damage is done. Then I connect a 6' leash to a carbiner on the pulley.
2. My other set up is simply a 6' plastic coated cable with loops on each end. I wrap the cable around any fixed object connect and them with a carabiner. I then conect the 6' leash to the cable with another carabiner. The trick is to make sure the cable can swing around the fixed object so it doesn't get wrappd around the tree.
We also use the fold up dog beds made by Coleman they work great.