I wonder how is it even gonna work. Ok let's imagine that old prices remained unchanged, USF can get full tier unlock and LV in first 5-6 mins, having access to major at this time is OP AF, almost all of his abilities should be gated behind T3 unlock, meaning that it will be a dead popcap weight in your army.
Simple fix is just to break all the rules and let the tier unlock without providing the major unit and make him the 120 fuel sidetech. This is the Twilight Zone after all.
On top of that cost of LT+CPT should be equal to the cost of full T1/T2, other wise there will tech rushes.
But you can tech major after getting LT+Cap anyways. Nothing's changed about timing except you can get an LV.
In the Twilight Zone, said M8 would likely cost a bit more in fuel, and have a bit less reliable main gun. Clearly something you would prefer to have the Stuart over.
The M8 as it is now has a worse gun than the Stuart but can still reliably pen any LV at long range (save for the luchs). It would have to have been nerfed a little.
If anything, USF could have had T1/T2 discount ones T3 is unlocked.
Maybe in the next episode...