I have a mate who is an old panel beater and a very good welder cleaning very important as Bill says My mate has fixed holes like that before for me. Cut out a plug with holesaw in material you can find (Land Rover correct try and find a breaker you only need a few square inches)( or maybe someone in your section has a piece of old guard -that happened to lucky me )and make a good fit to hole you dress in guard. Then my mate takes it to his mate the very good welder to get it done right Also best to make a doubler or another piece maybe 2 inches wide curved to fit across the guard to reinforce that area with the bolt each side going through strut,guard,doubler and then a wide washerSomething like this might do ok.
No Land Rover to hand but do have a Propane gas bottle and blow lamp.
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