Nope. I have done this in most of my cars, sometimes permanently, sometimes temporarily while I waited for the cage to be delivered. Vitara seats fold down so provided you don’t need extra head room for the dogs, you won’t need to remove them. The only reason for putting it back to a four seater for MOT is so the rear seat belts can be checked.
The only thing I would say from horrid experience, is if you are going to fix the guard in a way that it wasn’t designed to be fixed then please do make sure that you fix it very very securely. I had one that collapsed on the dog, which was my fault entirely. He wasn’t hurt but it terrified him and he vented his anal glands in the car, poor boy.