I had the same situation in Northwest PA. I was set up with a 110/119/61.5 setup, and my neighbor's trees grew very large and completely blocked my 119 signal. There was no place else on our property to put the dish.
The Dish service guy that came out to look why our signal was so weak explained this and suggested I switch to the Eastern Arc setup, and Dish agreed to do it for free (with a new 2-year commitment). It was the service guy that made the call and set it all up, explaining why I needed this EA setup. Without it, I would have had to drop Dish also. I don't know if they would just let you call and make that "orbital" switch. Probably not.
The Eastern Arc elevation angles are WAY higher than the Western Arc, so even though there are fairly large trees across the street for me, the installer said those trees would need to grow another 20-30 ft before they would be impeding the signal.
They swung my 61.5 dish over to 110, (because that's where the Youngstown, OH locals are), so I lost nothing, not to mention they threw in a 722K upgrade at half price for my trouble.
That's how I got around the tree issue.