Hey, I think adding the Doorknocker and the 45mm would be an awesome addition as historically these guns were extensively used on the Eastern Front. However there will probably some problems with their implementation. On your proposal, I believe it's a bit strange for an anti-tank gun to fire exclusively or mainly HE ammunitions instead of AP rounds, and firing at infantry wasn't their main purpose (however, the Soviet 45mm guns - I'dont know much about the PaK36 - were issued with HE and canister shots to use against closing infantry). And on the other hand, if the devs implement these guns and make them fire AP only, that would make them pretty much a nerfed ZiS/Pak40 with no almost niche (AT rifles do well as early-game AT), and if it's shells are equally good against light tanks and infantry, it would make the light gun a cheap, spammable universal unit, and I don't think we want that.
In fact, if we want to think of a way to implement these guns and find them a role, we have to come up with some abilities for these units to be useful and appealing to the players.
One (obvious) idea is to give the light AT guns the canister shot (like the one British Stuart has). I know it's not very original, but, hey, why not.
Maybe a Stielgranate-41 (there's a picture and description in the Wikipedia, look it up if you're interested ability for the PaK-36? It could be a one shot ability with a munition cost that would make the gun fire a single shaped charge with massive penetration and increased damage at an enemy tank.
Speaking of HE shells you mentioned, how about making them a ability? Once you activate it, the gun would fire HE shells, similar to mortar shells, for a small amount of time. Kind of a reversed ability of the US' 57mm gun.
The distinctive traits of these guns were their small size and relatively light weight, maybe the devs can play with that? A camouflage ability (not very new, also already used in the PaK38), or an ability (activable or a passive one) to turn and move the gun much faster.
Another solution can be implementing these guns as emplacements. I think the devs are already planning to do this for the PaK36. While having a lot of static emplacements is generally not a very good design idea (*cough*brits*cough*
), this idea also has it's pros.
P.S.: A fun historical fact:
Did you know that the Soviet 45mm AT guns were mockingly nicknamed "Farewell, Motherland" by their crews? The gun was called like that because being it's gunner was one of the most dangerous tasks for a soldier: you're in the very frontline (you have to be extremely close to an enemy Panzer if you want more than scratch it's paint with this little gun); your only protection is a small shield that probably wouldn't even stop a bullet; and you're always a primary target (in fact, a sitting duck) for everything the enemy has. In fact, there actually are some reports stating that this nickname wasn't used until after the war, but nevertheless, it's an interesting fact to know, don't you think?
