45 degree Elbows - Easiest method

We work in wastewater, and use 45 degree elbows on our lines. In order to optimize the design, we obviously want (2) 45 degree elbows back to back (HDPE piping). I haven't found a good way of laying this out to prevent a short piece of pipe between the elbows or not enough room for the elbows. Is there a way to route my lines with 90 degree bends and then add 45s and have the lines accommodate this? Even being able to route my lines then chamfer the corner with a specific length for the elbows (which wouldn't be ideal because I would have to know the length of each elbow) wouldn't be terrible, but I cannot figure out how to do that.

Any help would be GREATLY appreciated. Thank you!