Is there a defensive player position restriction in SP (NOT Coed)? That is, can a team have 5 infielders? I cannot seem to find anything that limits the number of infielders a team can position (again Coed aside).

Exactly. Excepting Coed, the only rules restricting player positioning is the one that says only one player (catcher) can be in foul territory at the time of a pitch, and the one that defensive players cannot be in the line of vision of a pitch. Anything else is legal.