I am assuming that in this view, it is where you are planning on putting the building and that is your house we are looking at? Just remember..what you can't see of the house from the garage, you also can't see the garage from the house. Secluded is nice if you are a mile back from any main road, but you have two roads close. It's just my opinion, but I think you would be much happier in the longrun, if you had a clear view of the house to the garage and visa versa. One, just for the safety aspect of it. If you are out there working, at least the wife or kids could step out of the house to see if you are safe.
Another thing to consider is that it looks like the majority of the trees are some type of evergreens. Fast growers. You could cut some down and replant behind the garage to make the garage secluded from the roads. Or if you wait until fall (which isn't too far away) rent a small backhoe and move all what you have out of the way. Again, that's just my $.02 on it.