Looks really great. Nice idea as well adding the lines directly onto the meshes as this makes hidden lines easy to hide :)
Ref the line thickness problem, have you tried to remake them on the fly based on the distance from the camera? Or rather than remaking them, what about reposition the line vertexs to make the lines thicker depending on the distance. I wonder what impact this would have on the speed. It might be acceptable.
In my routine I redraw all the lines every frame, and the only time I need to scale them is when I use camerazoom. It's fine for what I need but then Im not using a full hidden line routine. Perhaps JoeGr could point you in the right direction. He has full hidden line routine, but I not sure how it handles line thicknesses.
Ref the line thickness problem, have you tried to remake them on the fly based on the distance from the camera? Or rather than remaking them, what about reposition the line vertexs to make the lines thicker depending on the distance. I wonder what impact this would have on the speed. It might be acceptable.
In my routine I redraw all the lines every frame, and the only time I need to scale them is when I use camerazoom. It's fine for what I need but then Im not using a full hidden line routine. Perhaps JoeGr could point you in the right direction. He has full hidden line routine, but I not sure how it handles line thicknesses.