Can we protest a game after the end of the game?

Question
In our league in Colorado we have a written rule that states "All players in uniform who are not injured or being disciplined at game time shall play a minimum of three defensive innings of the game".
In our semi-final game this week, the opposing team had 2 players who played 2 innings or less.  Subsequently we lost the game in extra innings.
I did not protest the game until 1 hour later and the Championship game had already began.
After the game when I realized they left the weaker players on the bench to sway the outcome of the game, I first wanted to confirm with a player on that team that she in fact only played 1 inning.  She openly admitted this to me.
When I went to protest what we perceived as cheating the board members talked about it and said 2 things: 1.  I should have protested before the game was over or before the Championship game started and 2.  They said they come to this conclusion because even though there are no guidelines in our league rules on how to protest the game they drew this conclusion from High School Baseball rules.
I contend that because they were cheating by not playing their weaker players in order to sway the outcome of the game, that I should still be allowed to protest  that game.
By the way the same team only played that same player 2 innings in the championship game and the board was aware of it.  However they did lose this game.
I don抰 want to sound petty but please understand that all teams are required to give equal playing time/minimum 3 innings to each player because this is a Rec League.  All we are asking the league for is fairness and that there should be a consequence for cheating.  I always made sure that even our weakest players played at least 4 innings.  
Please let me know  if you feel that this is a situation where a team should be able to protest this after the game has ended and what the officials High School rules are on protesting game.  Should the team did not abide by the rules have to forfeit one or both games.
Thank you.

Answer
Charlie,

There are no rules that pertain to this type of situation, simply because the "must play" rule is only found in youth leagues. Therefore, rules on protesting these situations should be handled in league-specific rules.

That said, I know that high school games can be protested after the game is complete in similar situations. These primarily deal with situations where a player was in the game that was ineligible to play (not on the official roster, mandatory suspension, etc.), and not on a minimum-play rule. This rule is set simply because an opposing coach may not know before or during the game which players are eligible to play, and only finds out the issue after the game is complete, possibly when reviewing the scorebook or stats from the game.

I don't know how much time is given on these, however.