I generally use the Joshua Tree anchor system for toproping, as taught to me by a professional guide. Essentially, a static rope is tied to two anchor points to make a "V" shape of 90 degrees or less. If the angle is greater than that, less and less force is shared between strands.
I came across a climb I want to try where the only natural anchors are trees far to the left and right of the top of the climb. If I used a tree from each side, the angle of the rope would exceed 90 degrees. If I used two trees from one side, the direction of pull would be wrong. Bolting an anchor isn't an option in this area.
Is there a reasonable way to set up an anchor here so that I'm not putting a nearly full load on both strands? The only thing I can think of is to use two independent J-Tree systems (a "V" on each side). The two systems as a whole would have an angle greater than 90 degrees, but each side would be almost twice as strong. Is there a better way?