My secondary or side idea to go along with the above, is to change the Tower Defense aspect of the game. Since the maps we get are a single area, don't start with any traders. Build a basic compound and "find/rescue" the first trader. After they move into the compound, every seven days, the hordes attack and you have to defend the compound/trader. After that, you can "find/rescue" the other traders(one of each type) and expand the compound. The first trader just sets up basic shop, each following trader adds to the compound, including potential wall/tower guards(?) for protection from random wandering zeds. After you "find/rescue" all 5 traders...well...much like current late game, just repair, upgrade...wash/rinse/repeat. Though, with the wall/tower guards, if any are lost, you can go out and "find/rescue" new ones...definitely have a limit on how many, but could be an interesting resource.
Always irked me that we can have a basic wood/cobblestone base set up across from the trader compound, that obviously has a heat generation higher than we do, but the zeds always only go after the player. Would make more sense if they went after the compound and you had to defend it.