>>695998First, the stainless Opinel will be more difficult to sharpen than carbon steel would be.
Sharpening is mostly technique. The DMT mini-hones and similar "pocket sharpeners" are excellent for putting a functional edge on your blade in the field, but they aren't ideal for get the knife razor sharp.
All of my Opinels have come extremely sharp out of the box, so recreating the factory sharpness with just the DMT isn't realistic. Somewhere down the road, pick up a few nice bench top whetstones of increasingly fine grits. Using a freehand sharpening stone is still about technique primarily, so don't get frustrated if it takes a while to get your knives as sharp as you like.
Another great option is something like a Spyderco Sharpmaker, these require a little less skill than a traditional whetstone.
Alternatively, you can get a fixed angle sharpener like a Lansky or Wicked Edge ($$$$).
Use water, or nothing. Don't oil your DMT
good luck.