There’s a mention of this on the SSL website advising altering the inner profile if I recall correctly. On my 2018 car the factory cut out is still sloping upwards directly above the axle and the high point of the profile is not directly above. Sorry, struggling to explain without sketching, but, it is as though the axle has been relocated slightly at some time but the profile not changed to match. I had witness marks on the plywood on the sloping part of the cut out.
Thanks for advice, will check that next time rear wheels are off.
Richard
2018 Roadster 3.7 1966 Land Rover S2a 88 2024 Royal Enfield Guerrilla 450 1945 Guzzi Airone