When making my castor mounds,I pick the spots that look good to me--cuts in the bank or shoreline--penninsulas--anything that is different.
If the shoreline is all the same ,i try to set near chew sticks,pull outs or wherever they may be cutting.
I leave my springs of my 330s--straight out to the sides.I then block off the sides from the 330 back to my mounds.You can put sticks in an X over the top jaws of the trap.When the trap is totally submerged you can also put a dive stick over the trap ,in addition to the X sticks.Your mound and lure will do the rest.
Keep me posted on your results and please ask, if you have more questions.
Good luck and thanks,
Tom