I'm not sure that we are all on the same page. I, at least, am having some trouble working out what's intended.
Certainly didn't follow ratstar's explanation, sorry.
On your diagram when the switch is open there is no bias on the gate. So, the gate capacitance is charged when the switch is connected, then floats. There is discharge path for the gate charge on the gate capacitance. If the simulator model FET is reasonable, and the switch ideal, this will cause the gate to float at the previous gate voltage, 5volts, for a long time.
I'm no expert at mosfets, but maybe look up biasing them to see how its normally done.
The 2n7000 data lists a leakage current (gate voltage zero) of 1 microAmp, going up with temperature. It will be higher for the power devices you were using. Don't know what sort of capacitor values you are wanting to use, and not sure how long you want the charge on the capacitor to stay stable, before refresh, but 1uA is quite small.
Regarding numbers of transistors in circuits, I don't know what you were looking at, but it's not common to build these things form discretes. Equivalent circuits are often of chips, where it can be cheaper to put in another mosfet or four than to put in a resistor. So not always easy to interpret.