The concept you put forth of a limit varying based upon multiple conditions would actually be more arbitrary and subject to manipulation than simply having a fixed number.
Quick recap any team is hurt by using home runs for solos and two runners versus 3-4 runs unless it is a walkoff situation. Varying the home run limit per game at a tournament is more subject to manipulation than a fixed max. And to be clear that is exactly what you are now suggesting. Even BLD fields are not uniform in dimension and heat/humidity can vary by the hour. So an 8 in the morning game on a BLD Polo Ground field will have a different limit in the same tournament from the 12:30 game on Fenway both of which will be different from the 11pm game on Yankee.