Its not really the temp, as much as the sag. i usually sag .06 about 3 inches before i pull it so on a .09 i would guess about 3.5 to 4 inches of sag. You want it to ripple like a water bed when its hot enough. Then pull it quick.
I assume your vac table is a clamshell style. That has always been a problem with those. to get enough sag you almost have to touch the heating element. SO you can put your parts on risers. you'll get better definition high and the bad definition will be on the riser. hope this helps. Plastic aint cheap.
one tip. hotter is better. If you get webbing(lines that pinch together) you went to hot.