I tried the belt tensioner on the bottom where I first put the battery stop and it fits nice the spacing is perfect from the stop on the servo mount to the stop on the belt tensioner. The battery sticks out past the chassis exactly the same from end to end. I just might leave it that way and see how it goes. I'll post a pic but it didn't come out very clear.
I wanted to ask also if I open up the upper deck just 2 mm can I get the pully out without removing the upper deck? Inquiring minds want to know!
Just my 2$