It'll be a battery swap. There was that video of emergency battery pack ejection for battery fires, then you need a loading mechanism.

I haven't tracked LeMans much, I know the Toyota hybrids have been dominating it, but is it unrestricted hybrid drivetrains? Can builders make any kind of hybrid / regen / battery size / recharge drivetrain?

If not, I'd love to see what builders can do with go-nuts hybrids: wankel compact recharging, max-solid-state chems, etc.