I know this is an old thread but this is exactly the idea and I have used one on my 2000 FLHTC.
Not something you want to put full power too,it's just a dealeo to get you off the side of the road and baby it home or somewhere for a proper replacement.
Simple finger joint connection with allen screws holding it together,came with a plastic fisher tape to pull it through the primary.
I found this thread looking to see if they still make these and if I could find one for my new 2019 FLHT.
Doesn't appear that they are available for the newer bikes.

 

We made it from Gardner, MT. to Mandan, ND. on a replacement belt. And that was pulling a trailer. Right hand drives are much easier to replace and you only do it once.

 

Are you talking an emergency belt that has to be spliced together like the H-D kit?
Of course right side drives are easy like on a Sportster but the topic is H-D big twins with the pulley behind the clutch so not a roadside repair job.
That's the whole point of a splice together emergency belt kit.