Things I would consider:
1) You might need to create more curves in the long direction to control these bulges and wrinkles.
2) Use the same number of curve entities in each section so they will transition better, thus you might need to add more individual curves in some sections.
3) I recommend using conic curves instead of simple radii or splines
4) Use your imported cloud data as a template and create all your curves from scratch.
5) If you can, you might try to space the cross sections further from each other.
6) Create composit curves from the originals and use the composite curves to create your boundary curves
7) Doesn't look like an issue for your part, but don't try tp make sharp or abrupt curves that tend to influence to trajectory on the other side of the adjacent section curve. If need be make a feature square (like the end of the bottle) and add radii later.
Thats all I can think of at the moment to consider your surfacing issues and techniques.
Good luck,
Mark A. Peterson
Design Engineer
Ramteq