Hmmm...well, under those circumstances, you could do with one more simple VCO to beef up the sound out of the Rubicon II or to do audio-range modulation. Doepfer has their A-143-9, a quadrature LFO that can work well up into the audio range, plus it outputs four different phase angles of its sine waveform, so that if you wanted to use it as an LFO instead of a VCO, it can have the original phase curve modulating one thing, but your choice of 90, 180, or 270 degrees out of phase to do identical-but-offset modulation elsewhere. Small and cheap, too.