Photo of the car isn’t taken every time it goes into the dealer. It’s taken at MOT time along with the inspection this lets Motability decide what avenue to sell the car on either by their own site MFL Direct or via Auction. If they sell via MFL Direct they use the photo taken at MOT time to advertise the car to other dealers.
only other time a photo is taken is if having a early termination which they will take a photo when you order another car. For the same reasons as when it’s done on the MOT.
but I very much doubt they will allow you to modify the car.