Strengthening Observatory doors

I'm going to modify an Arrow Shed into a roll off roof observatory.
( The Oakbrook : 10' x 14' )
I'd like any ideas about reinforcing the flimsy sliding doors that come with it or even constructing/installing something completely different.
Any thoughts as to whether I should put entrance facing North or South?

Bryan, My first obs. was an Arrow 10x8. and the doors were very flimsy, and not very secure! if you push and slide them you can open them even if they are locked together! I never got around to a fix because the wind took the roof right off! and I decided to make a dome. But if you can make them lock to the channel so they can't slide when locked! 8)