If I leave the game mid run, as in going to the title screen, since the in game timer stops, would I have to use RTA or would that just be not allowed? I've found something pretty interesting but it's a difficult trick, and if you don't get it right you have to go to the title screen to try again. If I do have to use RTA, do I have to have a timer on while recording?

I think it should be fine, Not like you're pausing the timer and actually making progress.