The problem with tap tempo tremolo is that errors in the tap time accumulate, so if you're playing to a click, the tremolo rate will get more and more out of sync. If you need the rate to be completely in sync, connecting MIDI to the control port is probably your only option. Barring that, you could use a bigger ratio like 1:2 and tap half as fast. This would have the effect of halving the tap error. Moving to a ratio like 1:4 and tap a quarter as fast would be even better.