I'm also planning something similar on the long term. Mainly to escape the rainy conditions and have the scope a few 1000 km's further to the south.
I think if you have a really automated observatory, you should put more $$ in the pc's. You really need some kind of ups so you can park the scope & close the roof when power shuts down. I think you'll need some kind of stable and powerful server that is powered on nonstop.
Or some kind of electro-mechanical interlocks... Last year with some friends I made plans for an automated observatory and we thought about some kind of slipping cover that could be closed by its own weight in case of missing power.
Yes I agree, I run indi + kstars on a full desktop PC in the observatory. It was a cheap desktop but much more powerful than an RPI. I dont leave it powered on though.
I still have an RPI as a jump-host which is powered on all the time. I can log in here and then do a 'wakeonlan' to power on the main PC. Then I use teamviewer to access the PC from my home 50km away.
RPI is cool and all,,, but I dont see the point of trying to run indi + kstars on one. If you have space and dont need to move equipment then just get a cheap desktop PC.