You won't be able to dive at SJ on 28th with your schedule because the daily transfer is on early afternoon.We are arriving at DPS late afternoon/early evening on April 26, too late to catch a flight to LBJ unfortunately. So our plan was to fly to LBJ on the 27th, dive the 28th through the 30th, and fly back to DPS on May 1. Then we'd go up to Ubud for a couple of days before our flights out late afternoon on May 3.
Your best bet is to find another land based operator in LBJ.
I assume you are not interested to see the Dragon?