Q.Extending a trumpet vine.
I have a huge trumpet vine that grows across the whole 20′ front of my deck. Total height is about 9-10′. I am about to extend my deck 8 feet over the base of the vine. To keep from having to dig it up I want to unravel it from the deck railing, lay it down and build over top of it. When I’m done, quite a bit of it should stick out the front. I want to train that part to climb back up while leaving the main base of it underneath the deck where it’s always been. I may go a step further and cover the base so it won’t throw any babies up through the deck but there should be quite a bit of it still getting light. I am in Tennessee and the vine faces the south. Is this a workable plan without killing it?

Certified GKH Gardening Expert
My experience has been that they are almost impossible to kill. And if one vine does expire, there are plenty more coming up nearby. So, I would go ahead with your plan, and if the vine doesn't make it; I'm sure you can transplant one from nearby.
Also, if you wait till fall to extend the deck, you can prune your vine back as far as you need to and it should grow back quickly.
https://www.gardeningknowhow.com/ornamental/vines/trumpet-vine/growing-trumpet-vines.htm