From Boston
Telstar 5 is at 231.6 and 34.7 elevation degrees on the compass and Gal 10R is at 257.9 and 19 degrees elevation. This includes your magnetic deviation.
Both are kind of southwest from. Is the balcony open on it’s south end if so and you have no obstruction with in60 feet of the satellite location you should be fine. You might want to check out acusat.com, they have a demo software that figures this stuff for you. That is what I did for you...
Jim