Final Update: 19/10/14
Sorry for resurrecting this thread; I just wanted to thank everyone for their advice. My observatory is all done
Couple of things I added to the motel-o-scope design:
1. The temperature delta inside vs outside foam insulation is approx. 4°C.
2. The telegizmos cover provides rain protection and adds an extra layer of insulation on top of foam.
3. I intend on adding small de-humidifier and a small AC fan that keeps the air rotating.
4. The design is low key and doesn't stand out like an odd shape in the backyard.
5. Mount is locked on to the pier for security reasons and my optical tube stays indoors mostly.
When required the top cover can be removed for quick access to astrophotography. All electrical points are installed (underground) and have automatic timers.
The whole setup can be moved/uninstalled (excluding the decking) in case I decide to move.
I'd like to once again thank everyone who PM'ed me and gave me much needed advice.
Ciao