Air-droppable bunker is something of an ideal. Bunkers are great at ambushing, defeating a strongpoint, and holding a line. Paratroopers typically resort to ambushes because they are too slow to flank any other way and too poorly equipped to confront things openly. Paratroopers tend to just shut-down confronting a strong point. Oh, sure, they can defeat them, but always by taking the long way around. Paratroopers basically don;t have the numbers or equipment to attack from the front. Paratroopers are all about quickly taking a critical location and then holding it until armoured vehicles show up and nuke them from orbit.
Bunkers typically don't get to choose where they are. An ambush bunker will likely get discovered first, and even if it works once, it likely gets itself onto maps for its efforts. A more-or-less fixed, directional heavy position that can join in on an ambush is wonderful if you can get it.
Strongpoints typically don't put themselves in the path of a bunker. That ends up being a large part of why people use bunkers, to force the enemy to either make a massive strongpoint and blunt it, or to force it to go somewhere else because confronting a bunker head-on is terrible. A bunker or tank that was blocking an important path is a big problem, but if you can magically summon a heavier bunker with a bigger gun in front of it and just start shelling all day then it largely solves that problem, a slow vehicle can still be fast compared to paratroopers and forcing them to give up their position is generally a win.
Paratroopers typically stop functioning when tanks show up. No supplies, no heavy weapons... A bazooka won't break the front of a decent tank and if all you have are infantry then it doesn't have to worry about being flanked, and if all you have are A.P.C.s and they have tanks then you probably won't have A.P.C.s for much longer. If you can summon bunkers around your position then suddenly the enemy tanks have something that they can't just sit back and shell all day. The amount of armour that you can drop from a large transport plane is actually really impressive if you only have to cover the front of a one-man pod.
Assembly in the field is a problem, but it is the only way we can get anywhere near this performance out of an airdrop. And field-assembly is not necessary, it only comes up in airdrops, it can be surface-shipped to the front pre-constructed to support infantry more conventionally.And given all the options, a field-assembled vehicle is about the best. It can move itself once righted which speeds up the process of assembling the parts. It is much better than trying to assemble a long-range radio or giant gun or something that couldn't move. And given that the options are "mess about in a field with things that are not particularly useful right now" or "confront heavy tanks with satchel charges and bazookas" I don't see the downside to the assembled weapons plan. Certainly not perfect but better than nothing.
Superr-heavy, umm, okay, make that extra-heavy, I didn't check the list and wanted the thing above heavy...
Extra heavy is 100mm
iron/steel is, roughly, ehh, let's say 8 grams per cubic centimetre? 80grams per centimetre squared of 10 centimetre armour?
Reckless can carry 4 tonnes.... 50000 cubic centimetres... 5 square metres? You can do a lot with 5 square metres... or 3+1/3 square metres if you want super-heavy. That is, if you are only covering a gunner position. Let's call it a 2.2x2.2 metre sheet of extra-heavy armour. Sure it is cramped to put a human behind there and give them space enough to operate a gun, but then you go and make them sit instead of stand, it is not impossible. If we upgrade to Ice Giant only transportation then it is basically limitless freedom... Or we could try a sandwich of aluminium to reduce weight and see if layered armour is good for anything, but the price might be a problem then...
What we don't have at the moment is something that can tell a medium tank to go away and find something else to do with itself. We especially don;t have something like that which can be deployed with paratroops. We ought to have learned a lot about armour from The Vodka, so that should be easy enough. We have guns in the range, although I have no idea what the weight of a gun sans-moorings is, but getting whatever we can lift into a setting that can be deployed ought to do the trick, although it is possible that the barrel would need to be skimped on, which would be a sincere problem, but might let it fight in woodlands... It has been made abundantly clear that Salamanders are too light to be deployed alone. Now either we can try to negate that by some obscure means, which likely wouldn't work because we really need to drop the vehicle rating given how the game works.
...
I guess we could try to get a vehicle bonus from somewhere else? Give our infantry railguns to take out heavy tanks and trade that in for a bonus to our vehicle rating? I mean, yes, my proposal has problems. It will probably cop a big penalty to open regions, given how prone it is to being outflanked and how much faster proper tanks will be, but it ought to effectively address the absence of a heavy tank and also give a big bonus to paradrops. Unless it rolls badly, and nothing about it seems all that revolutionary. I mean, we already upgraded our parachutes, guns, and armour...