Although I believe it's good to err on the side of caution, I should amend the previous in the name of accuracy to say that you have anywhere from 20 minutes to over 90 minutes (depending on the rate of flood and degree of minus tide) to fish the incoming <b>IF</b> you are working back to shore on a high bar that does not get isolated by the flood.
A good example of this is the Saint's Landing bar, which (in past years) has been safe to fish as one back peddles directly to shore (directly south). If you started at the Paine's Crk lot, you'll need to walk the shoreline back to that lot. The lot that lays almost directly south of the trench is Saint's landing.
It's harder to get to the outer bar from Saints Landing because you need to walk west to cross early; it's harder to back peddle while you fish from Paine's Crk because there is no good fishing on the way back and the longer walk requires that you get out of there in time to make it back to solid ground.
If you really want to fish the outer bar, best of both worlds is to park at Paine's (pick a minus tide) to cross to the outer bar earlier in the ebb; then cross back to the tip of Saint's flat during the slack low, fish it sparingly at the point, then work it back on the flood and get out of there safely by fishing straight backward toward shore on the high part of flat.
You'll then need to hoof it along the beach to the Paine's lot.
As with all my posts, this is provisional and not intended for navigational use