I can confirm that it’s also not easy to use the ‘native client’ 
I think I am stuck where most of you are or were.
Getting past phase 1 might be easier in a next-next-finish way, but after that you also tinker with the low-level config - and you might find less ‘examples’ and 'how-to’s than for Linux as typically you don’t need to make any changes there.
I know one common root cause for the error I see - I even remember when that feature was added by Microsoft many years ago - but the usual fix does not help. In some sense that root cause is a bit similar to the ‘double V**’ so I wonder if it should work at all with that client … The nested tunnels is also something not too easily replicated in a test environment. That stuff is tricky to troubleshoot even if you have full access at both sides of the connection