high 5 for your formulae. ^5
Any 5V CMOS clock @50 Ohms ESR or so will work with a series R if one doesn't have a Sig. Gen.
Or Sig Gen with FM input for measuring DUT input impedance.
Getting back to OP's question, it would be easy to generate a 1MHz CMOS clock with a larger Series R as CMOS outputs are close to either 25 or 50 Ohms depending on type of CMOS, THen measure the square wave Vpp with a precision OP AMp diode rectifier with gain then input an ADC to measure the resulting square wave at a slow conversion rate.