I spent last weekend quad biking in Perthshire, which granted isn't wilderness strictly speaking, but it was great fun and there was plenty of stopping on top of hills to take in the fantastic Perthshire vistas.
http://www.perthshireoffroad.co.uk/I might have also destroyed a farmers fence with the misapplication of throttle. Danger and pretty views in equal measure!
You'd probably need a group of folk and some sort of transport, but it's local-ish, I think. A good start? Maybe someone more familiar with Norther-Scotland can offer something more useful :)
Andrew