I have a friend who built a little cleanroom closet into his Sprinter "mobile ski resort". Intelligently used, even a changing tent can become a mini-cleanroom. There are a few tricks to it, but they add relatively little extra expense or hassle. In potentially permanent clean room options, just study what tech clean room suppliers offer. For example, when doing fussy sheet film work, I wear a true all-Dacron cleanroom smock, almost completely lintless. They seemingly last forever and cost about $30, or maybe a little more now - less than a designer T-shirt. The walls are static-resistant black enamel paint. All the surfaces are washable via sponging. There's a recirculating true Hepa air filter in the room - a true industrial one I got free via architectural salvage, and a triple-filtered compressed air line coming in. Not a huge investment overall; but it sure makes a difference when needed.
Because that is my smallest darkroom, it's quite easy to heat in winter, so I do other things in there too, like enlarging. But the whole point is, once I transition away from fiber-based papers to nitpicky film applications, it's very easy to clean either the countertop or the whole room itself. That wouldn't be the case if there was a sink with chemical activity too in there, or a drymounting station - all that kind of thing, plus my really big enlargers, are planted somewhere else. Even well-thought-out conventional darkroom spaces should differentiate portions dedicated to different kinds of activities, with potential simple partitions between them, which do not necessarily need to be permanent, just easily cleaned.