I want to model a network geometry similar to the first attached part (Constant Depth Network_SWF). The network part of the design was created by extruding from a base sketch.

However, optimizing the design requires the depths to vary at certain points along the network. Ideally, SolidWorks would allow me to do something called a variable extrusion where I can choose the height of an extrusion at specified control points. Since SolidWorks doesn't have this capability I've explored workarounds like creating profiles and breaking the base sketch into guide curves so that I could either loft or boundary base/boss to construct the varying depths. 

The problem with this method is that because every bifurcation branches into two channels, I'm not able to smoothly transition the lofts from the parent profile to both the child profiles. When I try to boundary or loft half the parent profile to one of the children profiles and mirror it, SolidWorks doesn't allow me to do it because the mirroring face is curved.

Lastly, the dimensions of the entire device are defined by equations that require the input of a few parameters because I want to easily create many geometries by simply changing the parameter values. Because there can't be any sharp edges but I want to maintain control of the widths of each channel, fitted splines are the ideal way for me to round out sharp edges. When using the boundary or loft features, I can't use fitted splines so I fillet them but the fillets don't update dynamically. When I change the parameter values of the design, the fillets no longer recognize the edges they were once filleting and this makes it difficult to quickly create lots of different models or configurations.

I have also attached one of the varying depth models that was constructed by breaking the original sketch down into guides connecting profile sketches of different depths.