I have modified significant portions of most of the Trav rules. I use mostly other rules systems. Some detail gives me the flexibility I need for the game. Too many rules and steps stifles me. The 3I is a massive juggernaut, with an amazing tax base and thousands of SDBs in even minor systems.
Interplanetary trade is robust.
Many starports are huge city-sized affairs. The 3I is a powerful force to reckon with, with good control over most of its member worlds and the power to back its authority. Interplanetary trade is good on many worlds. Starports are planetary trade centers. The 3I is a stable confederation, held together by the nobility of its population, but not all-powerful and overall not wealthy.