By Nick Sommerlad Tyson Fury is eyeing a move offshore to the tax haven of the Isle of Man, the Mirror can reveal. The millionaire boxer has viewed a luxury mansion to rent on the island in the Irish Sea, where the super-rich can pay no more than £200,000 a year in income tax. Fury, already believed to be worth £50million, could more than double his fortune this year with some key heavyweight bouts. He chartered a helicopter to fly him to the £10,000-a-month mansion before Christmas, landing on the estate’s private helipad. An estate agent’s listing describes Billown Manor as: “One of the Isle…