You are confusing consistency and faction design. Each faction has its own trademark and OKW being able to built outside their base is one of their trademarks.
If OKW losing a T4 should deny their Tiger, then USF Major who comes with allot of utility should have an added 90 fuel cost and be required to be alive to call-in a Pershing...
Bottom line is that requiring T4 to call-in a JT or Tiger does not have to with balancing OKW that still have access to KT but has to do with the respective commanders and denying access to this units is not a good way to balance these commanders.
So is risk vs reward management.
If you're building it outside of base sector, you've evaluated that immediate gain is worth the long term risk for you and concede the right to complain when you lose the truck.
If you feel like its too much risk for you to handle, don't build it forward.
Is losing access to units worth keeping that noob away from that one point, knowing he will eventually nuke it with arty?
That's personal question to answer, not balance or design problem.
So that leaves only consistency.
Sorry, special snowflaking for OKW ended about 3 years ago, time to move on.