I think you're working off some incorrect assumptions.
Firstly the "fragile radar-absorbent coatings" you refer to aren't quite the issue you think they are - yes the B-2 is famously something of a garage queen (famously requiring climate controlled hangars and suffering a degradation in the stealth performance with each flight) and essentially cannot be deployed to a "rough field" base such as you describe. The thing with something like the B-2 though is that it doesn't need to be - its range (6,000 NMi, or 10,000 with one refueling) means it just flies from Andersen or from Whiteman etc.
Even the B-2 however is not solely reliant upon the Radar Absorbant Material (RAM) coating for stealth - a large portion of its reduced radar cross section (RCS) comes from its shape, and other stealth characteristics come from reduced heat, acoustic and visual signatures. "Stealth" is so much more than just slapping a coat of Dulux Radar Absorbent Paint on any old jalopy you've got lying around.
More recent "stealth" designs (i.e. the "Fifth Generation" fighters) such as the F-22 have a further reduced reliance on RAM skins as the understanding of radar reflections and the technology to compute it have improved. The F-22 doesn't require the climate controlled hangars of the B-2 and can be operated and maintained out of "normal" bases and hangars. Could it operate out of a really rough field? Don't know - if the USAF has tried they haven't mentioned it that I know of. I believe it was deployed to bases in Malaysia for operations in Syria.
The F-35 takes this a step further - Lockheed say that some of the RAM is "baked in" to the skin of the aircraft, making it much more durable and slower to degrade and the coatings are supposed to cure much faster than those used in the F-22, reducing maintenance turnaround. The F-35 certainly seems fairly flexible in terms of the environments it can be deployed in - operating from carriers, the UK, Israel etc.
TL/DR: with the exception of the B-2 the RAM coatings on in-service stealth aircraft aren't that fragile, aren't that hard to restore and aren't actually that important. And the B-2 would be extremely unlikely to ever need to operate out of the sort of base you describe in the first place.
 I don't think Dulux actually make RAM paint - but wouldn't that be a great talking point at dinner parties?
 I've not forgotten about the J-20, but the PLAAF hasn't exactly published much about it!