My nodal point trick has been to look out a window and paste a post it note on he wondow such that the edge of the post it (very close to the camera lens) is in line with the edge of a neighbor's house (very far).
You can approximate the nodal point through the viewfinder, but when you get close bracket a bunch of different settings (ex on a rail 34,35,36,37,38mm or whatever) and then look at all of them at a 100% view in PS and see which one is really the closest.
One you get the hang of it the process just takes a couple of minutes. I use a very durable waterproof nail polish and a paint brush and record the results right on the pano rail, so it is always where I need it.