I've had this on my "want to do" list. Not sure if Im up to the 47 miles or not. Definitely not in August. But, could be a Fall ride
Is there enough "points of interest" along the way to make it worth the long effort?
You could do an out and back which would be less mileage. I chose not to come back on the Lackawanna Cutoff and took the Paulinskill/road because the cutoff was kinda overgrown and had to duck a lot. I also ate more spider webs than on any ride ever. So yah do it in the fall/winter. As long as you stick to the rail beds everything is flat.
I think one of the cooler part of the cutoff (other than the viaduct) are the rock formations you see on either sides as you are passing through. It looks like they blasted their way through the mountains to make the rail. There some interesting bridges and streams/rivers along the way and a few abandoned structures.
There's enough loose railbed type of rocks on the cutoff that a plus size tire makes better riding. Skinny tires will get you through though. I probably won't do this ride again unless I am bike-packing toward the gap/PA or showing someone. It's worth doing once, imo.
https://www.strava.com/activities/1111393317
If you go East on the cutoff and not West, there's supposed to be a big tunnel (which is not really a tunnel) in Andover, I think. I might go check it out on Wed.