Type II MSD - Setup for NDAs

I want to use a Type II MSD whenever possible (mostly in USA and Canada). As you can’t discharge in some areas (NDZs), I’m trying to understand how I would optimally and legally stop discharge and hold waste in these NDZs. I’m pretty sure I could legally just switch between directing the waste to a traditional holding tank that must be pumped out while in NDZs and to the Type II MSD elsewhere. However, this seems potentially problematic as I’d have a rarely utilized holding tank in which I couldn’t keep bacteria alive, it would dry out, etc. probably giving me the smell issues I hoped to avoid by using the Type II MSD.

Could I instead somehow always go from toilets straight to a holding tank, and then have the holding tank flow to the Type II MSD when that’s permissible but close off that path off when in an NDZ? In that way, the holding tank would be in constant use and I could keep bacteria alive in it, acting as kind of an extra first biological stage for the Type II system. I’d still be concerned that I’m essentially back to the odor issues common to a holding tank. The only thing I could think of to help some more with that would be if I introduced aeration with a small air pump into the holding tank. One problem might be that, if spending prolonged time in the Great Lakes with that setup, the bacterial environment in the Type II would probably die from disuse and it would become a stinky mess.

Last idea I had was essentially the reverse. Direct all toilet outflows always directly into the Type II MSD to get fully treated but then have a holding tank after the MSD to divert the treated discharge into when in NDZs. In that way, no untreated sewage would ever go into that holding tank, so maybe its odor would be minimized. I’m wondering how water fully treated by a Type II MSD would smell when stored for a while in a holding tank.

I don’t know if there’s a standard, accepted, proven way to deal with this already. If so, I haven’t turned it up in my searching.

Also, if anyone with experience with any of the available Type II MSDs can comment, offer pros and cons, etc. that would be great. So far the ones I’ve identified that might offer sizes suitable to a full-time liveaboard for two people with periodic guests are: Ahead Sanitation Systems Ahead Tank AT-6T, Raritan ManaGerm, The Humphrey Sewage Treatment System 10A and the Enteron system by Tom Logisch. GNC Marine appears to make a variety of bacterial and water treatment products for use in the Type II MSDs but not the MSDs themselves.

Thanks for any advice.