What are you trying to do and why? If your objective is to remove lug nuts and fill tires a water separator really isn't something you need to mess with. If you want to do a lot of painting or sand blasting then water removal is an issue but so it compressor size.
So ignoring why, an easy way to deal with how is just to make a plug in filter station. Take a look at this picture
(link). This is a large compressor with a ~3' whip to a filter and regulator mounted on a board. You could do something similar. Use a short hose to go from the output of your compressor to a filter and oiler or filter and desiccant canister (note, if you use an oiler with a hose always assume there is some oil in the hose). That's it. You don't have to mount the board to the wall, you can attach it to the compressor handle or motor mount plate. There is no rule that you have to screw attach everything nor that you need to have a chain of things hanging off the outlet of the compressor.
Still, I would ask why this is a problem that you feel needs to be corrected.