RFPEW assessments for QMED

I’m currently working on getting my QMED rating along with RFPEW. The vessel i am on will provide me with plenty of sea time, but I won’t be able to sign off every assesment on the checklist. I know steam isn’t necessary, but I won’t be able to check off “Monitoring a water distillation plant.” Is this absolutely necessary to get the RFPEW, or can I still get it, just with limitations? Also would this affect getting the Able Seafairer Engine endorsement in 2017?