Hi,
It's unfortunate indeed. Could you reference these discussion, I would like to read them, I may be able to help you more on this then.
First, if you are targeting mobile, you will face memory warning issues if you load levels additively because of very bad memory leaks with Unity engine itself. So, even if you work very hard to remove spikes... down the line it's not a viable solution for large game content.
If you don't target mobile, then fine, but be aware that the memory leaks nonetheless are very much present anyway, so make sure you profile all the way to the end of your game and watch memory as you load and load levels.
You should create a system that handles your content and always knows what needs to be deleted and when. It's a huge effort and very costly to develop as there isn't really a generic way to do this, as the "level" paradigm is supposed to be exactly that...
-- Have you studied bundles? you could make smaller chuncks or data and they could behave better than asynch additive loading.
-- Or you need a custom solution using pooling and custom serialization:
-- using a pool system for your content is a known solution that works very well and prevent even spikes as content is spawned and despawned, so make use of pools where ever you can, it's the best way.
-- serialize your content your own way. I use xml ( via XmlMaker for example) a lot, I have a client mobile game project with 50K!!! lines of xml and it's a brease and faster then load additive, without the memory leak at all!!! more on this when it will be out
You can use a database as well, but in all cases, it's a lot of work indeed... and quite challenging if you want to do it all in PlayMaker ( but again possible with xmlmaker and database assets that are compatible with PlayMaker).
So maybe not the answer you expect, all this this to give a bug warning on spending time fixing something that may become obsolete because of other problems. so I would push the development to a point where you can finish the game more or less and profile the memory, then you can decide to invest time in address spikes, but in all cases, it will likely mean a lot of rework in the project structure, so always stressfull.
Bye,
Jean