dead ball area

[ggk]

american legion game - pro rules. at ground rules the home coach explains that there is an out of play line which runs roughly parallel to the foul line. he then states that "it's catch and carry" you have the catch the ball in play but then you may cross the out of play line into dead ball territory, but you must return to the live ball area prior to making a throw. i am BU, my PU says nothing so I speak up and explain that this is not the rule. i explain that as long as you don't fall down you can throw from dead ball area. coach takes issue and explains that this is how they play it at their field. i argue that a ground rule cannot supersede a book rule. i ask PU to weigh in and he hems and haws and says nothing. visiting coach agrees to play along with home coaches idea. i relent, but am annoyed a bit. i didn't want to make an even bigger issue out of it as i was BU and new to this particular league. the game proceeds w/o incident.
i am returning to the same field tomorrow and I have the plate. any suggestions as to how i should handle ground rules? should be fun.
thanks.