Not many here will agree with 3.e5 First off, pawn pushing without any plan loses games. Secondly, you need to develop your pieces in the openings. Kings are rarely checkmated by pawns. Black is not going to play dxe and help you out. He will develop his own piece playing his QN to c6. So should you and play - 3.Nc3 .....or you could play 4.Bb5+ which may be more along the lines of your thinking.
Fact is, the entire Sicilian is booked. Getting off the main lines may mean (simply) you would be playing inferior moves. No reason not to book up on the Sicilian since it is played so much of the time by Black. It would not be a waste of your time.
what would the best response for black be to 3.e5?!!
Thanks!