Bad idea, levelling was and is already is far too quick, only real gate is actually gathering the resources or having the gil to purchase resources. With the buffs they done you shouldn't really even need leves until around level 44, and that I blame on the cost of materials more than being a pure grind. I'm personally more inclined to say it should be a little more difficult to level, at least in Stormblood. I can say Heavensward is much more grindy, you can't just craft away.. Timed node after timed node..

I'm inclined to say that 55+ should be done entirely using House of Splendors. It's longer, but the amount of materia you can get from it...