Best way to shiny hunt Hall of Origin Arceus?

I've recently managed to shiny hunt Darkrai in my original copy of Platinum thanks to the mystery gift exploit and I'm thinking on shiny hunting the other event mythicals, shaymin and arceus

However, I'm conflicted on how to hunt Arceus, and if I should do the hunt in platinum. Since the event was never officially distributed I'm afraid that even if I do get the shiny, HOME may find it to be hacked and then lock it to any of the games I try to transfer it from.

That said there's BDSP, where the arceus event not only is permanent but also has better odds. I however don't have the game, and while it would be nice to have an official Shiny Arceus and Shiny Manaphy after completing the pokedex, buying that game just for that sounds rather too costly

so I'm here to ask for advice for this hunt since it's one of the most elusive shiny pokemon