I think the issue about airships being white rather than black is that heating up the envelope is something you don't want. Having too much lift, and not enough

I think the issue about airships being white rather than black is that heating up the envelope is something you don't want. Having too much lift, and not enough ballast, is just as much a problem as too little lift and no ballast to drop. The gas expands when warmed up, and the envelope can stretch to some point, but then you have to vent the gas in order to stop it from bursting. When it gets cooler eventually, you have to refill the gas. Model airship hobbyists often use a compressor to pump the helium back into a tank, to get the model into a transportable size. That might work here, also. Otherwise an airship must be stored in a hangar, or supervised 24/7 while filled with helium, even when attached to a pole.