To shorten a Rc31 by 20mm is easier than you think, if you can't or don't want to do it yourself Tim at Fork English will gladly do it for you & your 8yr quest will be over.
Ah!, it's changed since I last used it.
You could reach out to Italian members on here & ask if they could assist, luca73 is from Italy & ibbz is in contact with a member from there also.
It's a genuine Hope C2 no.2 caliper, the value will be reduced without the hub. If you wish to use the hub without the adapter you'll need to find a standard Bulb 135mm axle & non drive spacer, I'm not sure if the rear axles from non iso (yours) & iso hubs are interchangeable, the fronts...
Avoid that as they are really flexi & not fit for purpose, I tried one & bent it within a week. I then found a Bob Ibex for sale on here & Bob is still going strong 9yrs later.
Edit, forgot to add that the bag isn't seam sealed & leaks like a sieve.