You might be right, three full-blown VCO's may be overkill, but an LFO would be very useful and free up your other audio-rate oscillator for things like FM or a secondary voice to mix in. You also definitely need a couple of VCA's - one for the voice to fully silence once the main envelope closes, and one to be able to play around with things like bringing modulation in with an envelope, etc. There are filters (granted, with only one filter) that include a built-in VCA, like the SSF Pole-Zero or Mutable Instruments Ripples, but a dedicated VCA - or even one included in a mixer of some sort - is a necessary utility to have on hand.