More or less how my installs already are vs. solely one megamod or another, though I use parts of them.
Start from stock, and add what one desires. Some of my favorite campaigns are 8k, i.e.
But full interiors, ships, subs, etc. are going to eat up memory.
I.e., I could care less how a sub looks from the outside view. I use DD's old interior mod mainly because it handles the helmsmen better. I could care less about walking the entire sub length. I don't care about harbors. Other similar choices.
In other words, one has to decide what is more important; stability, faster loading times, reliable saves, etc. or something else, whether that's graphics or whatever.
It can be very difficult to have both in the game.
Regarding the damage model, I'd be happy if someone could change it to get rid of that silly ability to know your flak gun, etc. is damaged when you're submerged. Chlorine gas when the batteries are damaged would be good too.