All of the above--and if you have any option, go for the heaviest wall construction they offer, to prevent odor problems long term. If you can get it set up with two vent fittings. If one goes to the bow and the other to the stern, there's always a pressure differential and a breeze running through the tank, which oxygenates things and pretty much ensures you won't get odors.
We did same and have an unusual shape, and Ronco had many different types.
Aeration and good quality hoses are the keys to keeping the smell away. We had an extra vent hose fitting put in the tank and have two vent holes on either side of Haleakula. The aerobic organisms are the good ones in the tank, try not to put additives in which will kill it.
Also if you can, have an inspection/ clean out hatch put in for obvious reasons. Ours is 8 inches and large enough to reach in. While it an unpleasant thing to open it and use it, it is much easier than having to remove the whole tank should an issue occur.
Many claim to be good hoses. I like the Trident green stripe.
Peggy Hall is the guru to read on this topic. Your sanitation system is important, as one which doesn’t work, well makes it smell...can’t sleep and every cushion smells like effluent.
Another solution might be a flexible tank if your available space is too awkward for an affordable, custom made fixed tank. There is a difference in odor permeation with a flexible tank, so you need to make sure it is waste-rated—certainly not PVC.