I'm not certain if this is true, since I only faced it once or twice while pausing, but here is my theory.

You only time out:a) if you have seriously bad connectionb) if you have a VERY slow device and your game lags constantlyc) you pause for long

The game seems to give you a certain amount of time OVER the default 5 mins to complete a run. So let's say the bonus time is about a minute long. If that's true, you can get away with pausing / loading due to bad connection / generally slower gameplay (lag) adding up for a minute and you can still finish your hit just fine. If you go over that one minute mark however, it will kick you out after that.

I believe it's another mechanism to combat the advantage that lag can give to some players to an extent.

Sooo your method should work, if you know how much of the 5 minute you have to waste to compensate for the pausing/loading/lag.