50 feet is a lot. Assuming you have a decent compressor I don't think you will have any water in there. Since you plan on painting though I would run an air drier. I would plumb two outlets, one for the air through the drier and one without anything so you can run your tools without using up your drier.
Here is my set up.
I have ran it pretty hard and haven't had a drop of water in my air/water separator. I drain the tank and pipes after every use.