BEFORE YOU READ!
Sorry if I have bad english!
So as the Game Masters know a lot about the "upgrading" weapons system, and also about the Knight speed system (I.E. when someone use a normal shield or a striker shield in LD)
I thought million times this:
Why not making a new DLC?
A racing system, something like Races in the Krogmo King Arena
Using Motorcycles, Cars or even Spaceships...
Of course you need to upgrade your "movilizing system" in an alchemy machine like the one for the trinkets in the arcade in haven.
Upgrade the weels, chasis, gunning system, engine, direction and all that stuff...
You're basically asking for an entirely new game.
A small short minigame may work, but you're making it too big and shifts the main focus of the game.