Hi Bravlin,
I un-trimmed your surfaces and found a problem wilt the 2 faces shown in the photo they do not extend far enough to be trimmed by the vertical planar. Anyway having overcome that I made a solid of the body (no cutaways) and a solid to Boolean subtract (with cutaways)
to get the finished Solid.
The difference between top and bottom curves is 0.19 don't know how important maintaining this is ?
I generated the curves similar to how you have done but then extended them by using the extend tool.
This allowed spare for trimming.
Hope this helps
Barry