Can see both sides of the argument on the modification side tbh, on the one side, how could you think bolting something to the floor with a spreader plate that will impact the overall performance of the vehicle as not a modification, on the other side, you could be driving about with a piano in the back all the time which would also have the same effect, but ones a modification and ones not, it shouldn’t matter what’s the back, aslong as its within the payload and not enhancing the vehicle in anyway, then it shouldn’t be an issue.