you mentioned that there are illegal boats on the lake now. who enforces the rules?
I might go at it by saying we have residents now who exceed the limits. Nobody is doing anything about it so, lets included them and change the rules.
Also come in with some info on how fast a 175hp outboard boat goes on a typical fishing type boat. Make them aware that hp and speed are two diff. components and wake boats are all about grunt and not speed.
Maybe find out, if possible, why those specific limits were made and how long ago the rule was put in place. If the rules are very old, go it like its time to update to new modern boat standards. Get them to put a speed limit on the lake, not a HP reqment.
lastly, be prepared for them to bring up the fact that wake boats put out big wakes. ( maybe they dont know that yet ). This came up at our lake. Some univ. did a study, and I cant find link right now, that wake action does very little erosioin to lake shores. This study attributed erosion to wind, not wake action.