Traz isn't needed in IA to complete GE, GE provides plenty of troops for the battles you will do. What you need is lots of goods, so the LoA and/or Galata (level 10 or so), and Chateau (higher the better, 60+, IA is the best era for the Chateau imho) are great for providing those for negotiating through GE4, along with plenty of trading down with hoodies. I completed GE4 in every one of my cities from the first week I left BA, and in only one of them did I remain in BA for a prolonged period. Then once you have raised your attack enough to actually battle through GE4, you will already have enough troops on hand to battle without needing the Traz.
Traz IS needed for serious GBG battling in IA though, and by the time you are ready to put it down you will hopefully have gotten all your medal expansions from leveling your Arc first, along with the map expansions up to LMA (don't go further if you use a Chateau). Traz is huge, and that is a critical issue when space is limited.