Hi Matt,
Good luck with your project.
I have the 12" sw goto, the tube locks into position quite well, I manage to have my 2x Barlow + 5x power mate + dslr on there without too much trouble.
Whilst youre going visual you might be interested in the pics I've made with mine, below including deep space.
Cheers
Rusty
http://www.flickr.com/photos/80336656@N07/