Deckhand to QMED?

Apologies if this has been covered elsewhere, I searches on these forums but nothing I found seemed to answer my question.

I have worked as a deckhand on <100GRT ferries for the last several years. The crew contingent during normal operations is one master and two deckhands. As part of our duties, the deckhands are responsible for the startup and shut down procedures in the engine room, monitoring the unattended engine room with at least once hourly walk-throughs, and some minor items of preventative maintenance. In addition, deckhands may also assist the marine mechanic in dock-side maintenance and repair tasks.

My question is this: can I use my seatime working in this capacity while holding a MMC to fulfill the “180 days of service in a rating at least equal to that of a wiper or coal
passer” requirement for QMED ratings? If so, what sort of language should I ask my employer to use in a sea service letter?