You'll never have issue with gold on DMM.
Here we have gold up campaign, wait for it come and run the Morimori map on Saturday like you never run it before, you will get nice amount of gold from it.
If gold up campaign is 2.0x I think you should get around 60k / round maximum, didn't run it for 6 month not remember.

In the past you can pick helper for that special mission, I think you have to wait a bit to tackle it.