Moon Photography help needed (OMD)

With a 150 mm lens the moon size is about 10% of sensor size (400 pixel with OMD), 
40 % with a 300+2x TC, you need around 1200 mm to fill the screen.

The cheapest solution is a small scope:



OMD + small scope

OMD on small (10cm mirror, 1100 mm eq) scope