On further inspection I discovered that the high scoring letters H and K were still out and that HIKES or something similar on the triple already open could give the opponent a nice score.
So taking this into account the best option is to play off one or two letters, and aim to go out with a bingo. Playing DE at H3 blocks the possibilty of HIKES, or HIKER and makes a second opening for a bingo.
After simulating the situation in MAVEN, DE at H3 is clearly a strong move and most likely the best move in this situation.
As it happened my opponent had the letters for HIKER and made it after I played CREDITS.