Welcome to this "monstermaniacs" site.
Concerning the single swingarm the best option in my opinion is to use one ready to install kit as showed by our friend Atommyk.
It is of course more expensive but will leave off oll the trouble coming from the diffretent allignement between the whells and consequent changes of the original wheelbase.
We have in our club several smart guys who actually fix one swingarm ( one for all NYTRO on its "Tuono Blu") and a lot more that are thinking to do it......