A high wing location is the equivalent of about 3 degrees of dihedral, so you need 3 degrees of anhedral to counter the wing location. With regard to rudder roll coupling, the following are the cases:

High wing, sweep back and dihedral cause roll in the direction of rudder
Low wing location, sweep forward and anhedral cause roll opposite to the rudder.

This being the case, you need dihedral or sweep back in a low wing plane and you need sweep forward or anhedral in high wing planes. I have used anhedral for years on high wing planes. I am attaching a few photos.

If you build a low wing plane with no dihedral or sweep, it will roll backwards to the rudder. I have shown this several times to people who built planes that way.

If the LT-40 had a 60 inch wing, you'll need 1 5/8" anhedral on each side or 3 1/4" total. The anhedral on one side is half span times sine 3 deg. You'll need a scientific calculator.

The Big Stick 40 does not have enough and still rolls with rudder. I got lazy and just flipped the dihedral brace over without checking.

If you ever do try anhedral, you'll get lots of comments from people who don't have a clue. One person who hadn't seen one of mine fly, came up and told me not to fly because it was unstable and was going to flip over in flight. I went ahead and flew. If you ever have any ideas like this, turn a 4*40 or other low wing plane over and look at it. It becomes a high wing plane with anhedral.