(help) Offset of 2 venation pattern - trim - split - joining curves - to have just one surface into it

Hi,
My goal is to have just one surface. I created 2 venation pattern, then offset the resulting lines ( i tried in different ways with normal command and with clipper plug-in) but doing so i have some problem details as you can see in the pictures. I want have clean corners and then be able to trim-cut-split-intersect (whatever) between the 2 polylines offset. My goal is to obtain just one surface in common, into the offset lines



Venation pattern gh T005.gh (18.5 KB)
I tried to upload the rhino file but I don’ t know why it s not working. Into the rhino file there is a surface of 39.6metres x 2.5metres that is connected to the surfaces component in the gh file