Jon may be able to help you out. Otherwise, I suspect you're going to have to go second-hand, from Spain. The good news is that they were used on other Mototrans bikes - Forza, and I think Strada and the 500 Twins.
Try the search words, 'Soporte relojes Ducati'. That gives this,for example;
https://www.milanuncios.com/accesorios- ... 045369.htm(P.s As I guess you know, Ventos only have 3 idiot lights, not 4 as in this example (additional battery charge light). But the instrument rubbers will be the same).
P.p.s This one is NOT Vento, I believe:
http://recambiosducati.com/es/272-cuadr ... desmo.htmlHTH
Craig