As the bandwidth and frequency lie within the audio range, my goto for these sorts of signals is to generate them programmatically, or in an audio editor (e.g. Audacity, or my editor of choice, RX), then replay them through an audio DAC. Now my bench has computers as part of my test equipment, so this is easy enough for me, and I have a dedicated cheap 4 channel audio interface for generating such signals. This relies on you being ok with the square wave to be bandlimited to, say, 22Khz or whatever your nyquist is.