Most of the body type mods do NOT play nicely together. Most specifically the base body and the hands/feet. It appears that the head mods seem to work with just about all of the body mods, but not the other stuff. This also applies to any armour mods. 99% of them are using a specific body mod, and will NOT look correct on any OTHER body mod. You are forced to use the same sort of body mod that the original author used to create his armour or you will absolutely have visual issues. Breasts poking through, butt poking through, hands not connected to arms, feet not connected to legs, and a neck that has a circle around it where it does not connect to the body itself correctly.
Basically, any mod created to affect the body/hands/feet of a character SHOULD be matched, by the original author, to the different adult oriented/nude body mods, however, few, if any, ever bother to do so, they tend to only create their mod for their specific body mod preference.
Basically what is happening is the body sliders used on the main body mod, also affect the positioning of the verts for the outer edges of the body, IE the hands, feet, and neck joins. So, if the body mod author doesn't also mod the other affected objects, you will always have this issue.
A further issue is caused by specific armour mods actually duplicating whatever body mod you may already have in place, IE, you end up with a duplicated body because their copy is also displayed at the same time as the underlying base body that you have chosen. You end up with weird lighting/shadowing issues or additional duplicated body pieces poking through.
So, what needs to be researched you ask?
Is it possible to build the body mod, armour mod especially, WITHOUT embedding the underlying body mesh into the armour itself? So that we can eliminate the duplicated objects? It appears that the game overlays the armour on top of the body, which is how it should be, but it also appears that the armour mods out there that I have tested, ALL include a FULL body as well as the armour itself. I am wondering if this is absolutely required. I am hoping that this issue is caused by inexperience, not a requirement, where the mod maker is exporting everything instead of just exporting the armour.
I do realize that the armour is supposedly weighted to the body itself, but why would it require a complete, NEW COPY of the body to be embedded?