The T-34 in-game has armor skirts available, but are unused. Those were added by the Germans and would be a perfect fit for a German T-34.
I don't think any sane person would steal a Mosin, though...
Is there any way to see this, or could you post an image? That's very interesting. If it's schurzen-style it would make a perfect Vet 2 bonus if the tank using Ostheer Medium Tank veterancy instead of Soviet Medium Tank veterancy.
As for the Mosins, Germany captured them in massive quantities, they must've had over a million of the things, though I don't know what use they made of them outside of arming the Volkssturm. But my reasoning for Mosin-Nagants is twofold: the Conscript Mosin-Nagant is stronger than the Osttruppen Kar98 which is fitting for the "Advanced Osttruppen", and using Russian rifles fits the theme of the Doctrine; the theme of capture equipment.
Why do you need a Soviet howitzer? The German is much better - I would even say OP: it has better accuracy, rate of fire and just super OP 1st veteran ability.
And having two infantry units in one commander is a very bad decision. I think one ability is enough - "East Front veterans" which gives 5 people to the Grenadiers and SVT-40.
The Soviet Howitzer is because large numbers of them were in use by the Germans, it being bad is a balance problem unrelated to this suggestion, and should be rectified on it's own.
The reason for 2 Infantry units is I wanted to use both the SVT and PPSh, but the SVT alone is only marginally better than the Grenadier's K98, and worse at range. They'd only really be worth it if equipped on a larger squad, so I had the idea of giving them to an "Elite Osttruppen" unit, which itself sounded like a comical idea, so of course I did that.
For PPSh's Grenadiers do not have the durability to make good use of them even if they're the Shock Troop version, and if you add an extra man then it's basically Assault Grenadiers, so I just cut out the extra step and added Assault Grenadiers.
Now that you mention it, I can't think of any doctrine that comes with 2 Infantry units, excluding Officers. Except Partisans, but that's their entire purpose. I'm not sure what the best balance could be here.
I agree with Crecer, I think a captured HM-38 120mm mortar would be better than the howitzer.
Also to add to what Roastin said, the Germans also welded on Panzer III and Panzer IV commander cupolas to the top of the turret as well on captured T-34s:
The main reason I didn't go with something like the HM-38 is because 2/5 abilities were already call-ins, the ML-20 was the last ability I added and I wanted to avoid any other call-in units. Had it not been for the recent changes to call-in tanks, I would have been at 3/5 call-ins already.
As for the remodel I'm aware of that, but I was trying to utilize only existing assets when coming up with this. That said I'm very interested in what Roastin has to say about that extra armor.