another thing simple as it sounds for all my salmon rods (setups) back when i fished 100 days a year i would check each swivel knot with a 10 lb rigger weight its amazing even tho ya think every knot was done perfect ,sometimes ya miss wrap a line and it breaks real easy..even after 100's of ties i would still have a failure on ocasion ..better found in the driveway or floor of boat than after a 10 min fight....
run it down the middle like scott said ,,i did it for 15 years without issue ,ya aint gonna get any blowback from prop you will notice yer pole quiver a bit due to propwash I did it with a 2ft arm for 10 years till i got a 42 in ...But my rigger was mounted only about 3 in in from back of boat(transom)...be carefull deploying ball if ya have to reach out its easy to "drop" weight or swing it back into yer transom...get a retiver line ...