Creating geometry from curve from cross section

I have been trying to make any kind of flat surface or extrusion from a cross section without success, I have an assembly and from that assembly I am creating the cross sections then the curves from them, i don't want to use a sketch because this curves can change drastically then the extrude starts to complain.

On the image below (front view) the two "hills" can change to be from one to ten, so one curve feature may have one to several closed loops.

From this loops i just need to have a solid extrude either 2 or 4 inches tall.

My goal is to have something like the image below and that can be updated without major issues

Any ideas??

Thanks!!

Osiel Gaona