You can use a cheaper and compact ( and accurate ) directional coupler from;
https://cdn.macom.com/datasheets/CH_CHS-137.pdf
If you hesitate from the generated harmonics coming from your rectifier circuit, use a BPF to eliminate the others.
As a remark, a calibration method will be necessary in your measurement system due to non-ideal coupling response,filter ripple etc.
You can add also a RF Power Detector from
www.analog.com or
www.linear.com as a complementary for your project.You will able to measure the power as DC value in dBm scale.
There are double detector versions too in order to compare incident and reflected wave powers.