Use a P-channel MOSFET to charge the capacitor and you can then tie the gates together (low = charge, high = discharge). The source follower configuration you currently have would require more like a 10V gate drive to work properly.
No resistor is necessary with 47pF, however there is significant capacitance in the MOSFETs (even the smallest ones you can find) that will cause the voltage across the 47pF to behave differently than you might expect.
There is a lot of literature out there on making analog switches that have minimum coupling. If you don't feel like re-inventing it all, search on "charge injection" and switch. Also consider the source-to-drain capacitances.