Hi Cedricbe
It is fine to create views which are not defined by the vendor. Make sure you can differenciate your views from the vendor views.
In terms of the upgrades here's the things to watch for - the underlying tables may change names of columns so your views may break. Just make it part of your UAT testing to check the views on an upgrade.
Otherwise I think creating views is a great way of communicating with the ServiceDesk Plus database