Agree with twosheds, that way you got a lot of corners there and you'll get it cracked in no time... I've seen a modified offroader with a holed chassis tho. For weight saving I dont think theres much one can do on a landrover, maybe start grinding the axles, gearbox, engine.......
On aircraft weight is saved in many ways, different materials like composites, titanium, cres, aluminum (heat treated- will almost match steel's strength for its weight) but thats an aircraft...which is meant to fly, not a landrover...which is meant to stick to the ground!