Ballast as it is does not make the game "fair" nor "competitive". It makes it mediocre, specially the Elite Tier.
In my league, Elite tier has 90% under 30 teams and have some under 20. Most in PRO are 20 or under. I'm 30 in PRO carrying extra 11Kg.
One team in Elite has won, at least, the past 10 seasons and another team repeated second place for at least 5 seasons (just left the league). Both level 30, and I believe there are another 3 level 30 in Elite and that's it.
In the mean time, I'm in my second season in PRO struggling with ballast seeing how teams under 20 have the same or better chance than me to get promoted to Elite just to bounce back to PRO almost immediately or finish mid table at best for several seasons to end up leaving the league or dropping the game.
I'm pretty sure could be more fulfilling to be a PRO champ than struggle with relegation or finish mid table for many seasons in Elite.
Nobody wants to stay in PRO by choice, hence high level teams should get promoted fast to fill Elite with higher level teams. Your ballast approach is thought as if 20+ level teams would want to stay in PRO.
Ballast as it is, it's harmful. Either you remove it, make it (at least) optional (league settings) or calculate it in another way taking into account number of teams under 30 in Elite versus level 30 teams in PRO. Not just by adding it based on level cap.
You're penalizing oldest and committed players in favor of newest and (possible) non-committed players.
You should focus on making Elite competitive fast, not making PRO "fair".