My compressor is a California air type with 9 litre tank, it weighs around 16 kg and will sit on the floor, I have trouble with constant back pain so I'm not in a position to crouch down to it as often as I would normally be disconnecting my brush so the the quick connect at the brush suits my situation as does the MAC, I have to keep everything at the height of my upper body to avoid pain, for the same reason my easel has to be almost vertical.
My compressor situation is similar. I have a small California Air Tools compressor that's kept low (atop an upturned milk crate and a heavy book, to help prevent vibration from transmitting to the floorboards, so about knee-height). I basically keep it permanently dialed in at 60psi, and run a clear coil hose to this:
That's a heavy-ish steel bookend with a regulator, filter, and 2-hose manifold mounted to it (an Iwata hose and a Badger hose). I built it because I don't really have a permanent workspace, so I needed/wanted a portable "bench block". I plonk it on the table or easel or whatever right next to whatever I'm working on, and it lets me have my air control right at my elbow. The regulator is a 0-30 PSI model, so it gives me very fine control. Eliminates the need for a MAC valve, and the clear coil hose between it and the compressor proper acts as a pre-condenser for the filter (and as you describe, lets me visually monitor the moisture in the line) , so my air is dry even in humid weather. This lets me connect my brush hose directly to the brush with no extra gunk in between, without sacrificing control or filtration.
If I were to find myself in a situation where the humidity was too high for that setup to handle, I'd add another filter stage either to the block, or to the the hose between the block and the compressor. My logic is that humidity can't be reintroduced into the downstream line no matter what the ambient humidity is, so it doesn't matter where the filtration is as long as it's achieving the same level of downstream humidity. The further upstream the filter is, the more efficient it has to be, but that's easy to upgrade if need be, so it's not actually a big deal.
This whole thing was motivated by my severe dislike for having any extra stuff hanging off my brush, as I STRONGLY prefer pen-like handling to a pistol-grip handling. With the portable bench block and a lightweight poly hose connected directly to the brush, it feels more or less like I'm swinging around an unconnected straight-out-of-the-box airbrush. Very liberating.
Please forgive the zip ties. It's on my do-do list to drill and bolt the regulator & filter in place properly, but the "temporary" zip ties have been doing the job well enough that it's allowed me to procrastinate.
