I made some suggestions to help it scale in another thread that were well-received, so here's a poll.
Stuart Skillshot
The Stuart's Point Blank Engine Shot is an amazing ability on paper. However, everyone who's used it knows firsthand how much of a mess the implementation is.
A solution is to turn it into a manually targeted skill-shot, like the Firefly's Tulips or the Pershing's HVAP round.
Give it 150 penetration up to Range 10, then have that rapidly drop off to 0 by Range 20.
150 penetration means it'll penetrate the rear armour of anything (it's meant to be an engine shot!), but it can bounce if you fire it at the front of mediums up.
You've now turned the Engine Shot from an unusuable ability to one with a lot of tactical depth.
Stuart Smoke
Give the Stuart a smoke discharger ability like the AEC, but lock it behind Major.
This gives the Stuart the survivability it needs to function in the mid-late game without messing up the balance of the light vehicle phase.