Well, then there's the model that The Voice and other reality competitions use, which is basically that any block of the show that doesn't result from or directly involve audience participation is filmed completely in advance and only the live portions are done at time they need to broadcast.

Your host would need to be good at stretching or compressing to hit your time marks, and there might need to be someone with the sine wave for the seven second delay if needed. For someone like Carson Daly, with years of experience working TRL on MTV, no sweat. For someone else, maybe not so easy.