There's another option. You can buy a longer strut, however you must be careful to NOT buy one that's too long. The most you can extend the length is about .5" longer, which lets the door open about 6-8" more.
Here's the strut I bought which helps a little, similar to moving the strut ball .5" without drilling new holes. If you were to use this longer strut AND move the strut ball, you "might" be able to optimize the opening angle even more, but I think you'd have to move the ball location to the left a little, about .25" for added clearance for the door lip. This shouldn't be a problem for the collapsed length, as the stock strut doesn't collapse all the way in stock form.
The stock strut is 14.75", eye to eye centers. The one above is 15.25". The next size up from this company is 16.25", and it won't work, too long, I tried it. Even though the collapsed length works, it's too long when extended, hitting the door lip when fully open. This conflict would surely bend the strut shaft eventually.