There have been plenty of observatories that have been put into houses. Heat haze can be mitigated depending on the type of materials that you have already, eg tin roof although it gets stinking hot during the day it has an extremely low thermal mass and will release the heat its gained from the day in no time at all.
If you have bricks around, then your in a bit of bother as they hold heat really well! and hence why they are generally used as a building medium.
Are you wanting to get into astrophotography if not a nice little deck out the back somewhere is a far better/cheaper option. If your looking to go to astrophotography, its a different ball game.
I have done analysis on the different sections and which one proforms the best and they can be found
here