Custom seat bracket

Just bought GTI golf seats for my Ford fiesta mk6 and of course the mounting points to the floor dont line up was going to drill out new holes but one seat rail doesn't line up to the mount I was thinking of getting 4mm aluminium checker sheet and attaching the checker sheet plate to the seat with lock tight nuts and bolts and fastening the sheet down to the floor with the original bolts would this be secure enough I dont care about air bags or seatbelt sensors

Whatever you do make sure you do it right. You want to make sure the material you use is strong enough to withstand abuse. The last thing you want is to have your seat break free in the event of an accident.