I thought you could use N2KView to to trigger a DCR on something like a tank level? But I've never tried, so am not sure.
But even if you could, I would recommend against it.
First, I hate to say it, but the TLMs are terrible with gray or black water. Been their, failed, did something different. And know a number of other people who had similarly poor results. So the first problem is that the TLM is not a reliable level sensor, so definitely not suitable for subsequent pump control. On the other hand, their submersible pressure transducer coupled to a FPM100 works very well for gray and black water.
Second, even with reliable level sensing, I have not yet been able to get comfortable with Maretron for any critical control function on an unattended boat. I've had too many little issues with N2KView, some in Maretron, some in windows, and some in Adobe AIR, that cause hangs and require restarts or reboots. For something providing control, that's generally unacceptable. Now perhaps with gray water you can convince yourself that the tank pumps should only cycle when someone is on the boat because otherwise how would you be producing gray water. But you still have risk of a pump turning on when it shouldn't, and maybe staying on. N2KView has gotten a lot better over the years I've been using it, but I'd still be a bit uncomfortable using it for control vs monitoring.