Ummm…not done it on a Pro with pass-thru. But I think I posted how to do this with a link to a video that ShopBot did showing the same thing done with a CNC in the event what I explained wasn’t clear in text.
We’re I to have done it on my Basic PRU would have required an unsupported use of the garage door front of the unit which I can neither affirm nor condone 
Although that’s still limited by the distance between the top of your no-cut zone and the back of the machine.
I had to revert to the Redsail Wed night to cut some long multipart stencils that were 17.5"w by 28.5" long for an artist’s sidewalk painting public art project since the sheets were 19x48" they were being cut from. Hate having to do that - really looking forward to the Pro coming in someday.
EDIT: Here’s the post I did detailing a bit on how to index to do long material cutting/engraving.