When you say a big spawn gate, I assume you mean something like in trackmania.
No, I actually plan to do something like the Toad's Turnpike track on Mario Kart 64 where the starting line is separated from the track itself so the spawns won't be in the middle of the track when you're about to do another lap
As for respawning, there could be checkpoints that the kart respawn after falling sonewhere, I have no idea how I could do that so some help could be appreciated