Using the underframe it might be a little bit painful that the height of the guide is somewhat lower than it should be.

So I created a litte jig that you can clip on. Download combinations (25/35/50/75/100/125/250mm are offered for download) or resize to any length you want in your slicer, I found it easier to print a bunch of small jigs instead printing larger ones. You need 500+mm in total.
Just clip them on and remove them fast if not needed.
 

Print orientation as it comes from the STL file.