A smartphone or a tablet with internet connection is a big plus. Without is a much adventurous alternative.
I use a smartphone, with Android mirror to my double DIN touch screen car radio, complemented with a tablet+removable keyboard for planning and watching movies. You can also use a tablet with SIM and a tablet holder on the dash.
Navigation
Only some navigation app, take in account size and weight of your rig: I found CoPilot & Sygic. Monthly fee keeps me from testing it. Pop me a mail if you have experience with it.
So far I preffered Waze, but it does not offer sharing of points-of-interest between PC and mobile or showing POI's while driving or navigating/planning. This is much easier with google maps with a google account.
Finding campervan parking, service points
Untested: Campercar, CamperVanBible