Was editing my post and you replied too quick the way it is now, it's basically a light tank completely immune to bullets (except incendiaries) and with as much HP as any of the light tanks post-upgrade (and everyone gets the upgrade). It's not a utility vehicle, it's a shock- light tank like any other at that stage of the game imo.
Well, yes, it certainly is at that point which is why it's capable of snowballing games that hard with a rush.
But on the offhand chance it
doesn't for whatever reason, it's mostly just scouting and AT mines because it requires being so close to do worthwhile damage it'll probably be dead the moment AT goes for it. I'd be much more likely to micro an M3A1 into the enemy than an M20 past 15 minutes (Ok I still wouldn't do that one very often either but you get what I mean).
So basically we just need to nerf its initial power and I think it'll do as you asked for just fine!