I hope the title is somewhat clear, but if not, here's a picture to leave nothing up to imagination:

From left to right we have:
1. The initial shape, the red line is the stroke, and also the path of the object, while the black area is the fill
-Reshaping the stroke/path will cause the fill to reshape as well, just as would be the case with a rectangle/ellipse/etc
2. The desired result, here manually replicated by turning a stroke into a path, adjusting it, and then adding the "fill" as a separate object behind it
-I want this sort of result, but as 1 object, so that when I adjust the path, that is the outer stroke, the fill automatically follows suit, but 2 separate objects obviously don't work for that
3. What I've gotten with "Power stroke", while I can now adjust the width of the stroke, the fill is applied to the stroke itself, not the object as a whole
4. Same problem, just done with "Pattern Along Path"
-I can also get a similar result by just making a stroke, turning it into a path and shaping it into how 3&4 look, all of which are not what I need
There are 3 solutions I can think of:
1. There's a way to adjust stroke width dynamically while using this stroke of variable width to surround a fill, and I just don't know that way
2. There's a way to link up objects so I'd have 2 objects, one serving as the stroke, the other as the fill, but they behave together as one object
3. A plugin, sort of similar to "Power stroke", that adds separate handles to the stroke for width adjusting, much like the

I hope this is clear enough, and maybe someone has some enlightening words for me.