Hi Alan
Haven't taken my van there but have holidayed on both islands in the past few years and loved them.
However, some roads are horrendously steep/narrow on both - particularly Corsican coast roads, and frankly I wouldn't take my van over as good sites appear pretty scarce. Let me assure you I'm no namby-pamby on overseas touring!
Why bother anyway since there are some fantastic air deals going out of peak season (when you'd be insane to be there as they get so hot/crowded) and you can then stay in a pleasant hotel for less and for more time than ? Try Easyjet to Olbia for example and you can get a return for about