This is where having the factory manuals will save you lots of time...
the trim sender unit adjustment says put the drive all the way down and then adjust the sender's position to get the gauge to indicate fulll down position and then tighten up the retaining screws.
the trim limit adjustment calls for the drive to stop when the cylinder has extended such that the mounting eye center-center distance is 20 3/4". there is also an set of index marks on the trim limit switch that need to be aligned when the switch is installed...if you can't make the adjustment, put the drive down, remove the switch and see if the marks are lined up...