This request have been made couple of times already, i don't think there is way of changing the global rank like that. I did manage to make "open all roads" trainer, but it has side effects, nothing huge, but still.
also TDU2 hacks have already been discussed
HERE, like years ago ... you should start there and see thru it. im sure global rank was mentioned there few times and people tried it, but failed at it.
I don't think there is server side check, but there is more to it than simple value. In fact i have few ideas and i just might test them out, i think one of them will work, but it will take long time .. ugh not sure if i can bother with it.
If i do make the trainer / hack, you will hear and see about it on my YouTube channel, so keep your eye on Feed and see what happens.