I would suggest a mileage or mileage boost token which could be bought using in game funds. I've finished the game and I'm still about 30k short for the Around the World trophy. What I do have is lots of credits as I've bought all the cars.
Maybe something like 5k for 1,000,000 credits or a 2x multiplier for 500,000.
This would enable people who would like to pursue the platinum a chance to get it without having to change the trophy.