Weather balloons have been pretty standard for decades, so if you want to start using a markedly different kind to blend in with your spy balloons you'll need to establish their plausibility first. Like showcasing them at metrological conferences where you enthusiastically explain the real advantages of such a large platform for weather monitoring and show the results you're getting and so on. Otherwise it's as if you turned up at a bank's drive-through in a tank claiming that it's just your family car.