Hi Eric, a perminent observatory is a must if you want to get out every clear night with minimum fuss and stress. To have it in your back yard is just another bonus. It all gets harder with setting up when you get seriously into say imaging.
Many times I've walked out to my observatory and setup, began imaging, walked inside the house to begin down loads, then discovered the guide star was total lost. Walk outside, not a star to be found... close the hatch, shut down, walk back inside the house and then walk outside again a little while later only to find the sky is full of stars.....
Do this with a whole swag of gear a few times and you'll be kicking the dog...
When is a rainwater tank not a rainwater tank... ?
Here's a link to my observatory for the answer...
http://www.baytop-observatory.com/eq...bservatory.htm
Plus from the air it looks like a RWT so no council building fee.
Cheers
Rich