Add a "No Armour" Type in Unit Class Design. Probably should be exclusive for infantry.
Reduces unit cost by half of the default cost, thus where for a example a PWL with light infantry armor would cost 0.06 per unit an authentic imperial guard(TM) would cost only 0.03, with of course 0 Armour regardless of Tech Level. Maybe the cost reduction should be even bigger than 50% to make it something that can be seriously considered as a strategic option.
It is difficult to overstate how
tremendously OP this would be. Base ARM 1 on infantry is already usually ineffective unless you out-tech the enemy, as no weapon except for PWL has less than 1.0 penetration, so making infantry even cheaper by giving them "no armor" would make what are already a very efficient class of units incredibly dominant just due to how cheap and spammable they will be.
It is better to understand that ARM 1 is the base army uniform which gives whatever minimal armor level is appropriate for your setting, and go from there.
While we are talking about ground combat... I would propose to remove the Logostics module from Infantry or do some mechanic where you must have them and then make vehicle supply modules more efficient than infantry supply units.
Currently there is NO reason to ever use vehicle based supply units as Infantry ones are cheaper. You just use the reserve mechanic to replace the infantry ones when they are consumed or destroyed. They are way more efficient and thus cheap to use than vehicle supply units. I always ban the use of infantry based supply units in my games unless they fit the theme such as a special forces unit meant to operate independently or something.
I have found a good balance by modding the DB so that the large LOG component provides 1000 GSP (instead of 500) and restricting it only to LVH.
As it stands in the vanilla settings, there is never any reason for infantry to use the 50-ton module over the 10-ton module - they provide the same GSP per ton or per BP, but the smaller module allows more individual units and thus is more resilient to enemy fire. Thus, removing the INF+LOG (leaving only INF+LOG-S unit from the game is no loss at all. Doing this allows increasing the value of the large LOG component without upsetting the balance of infantry logistics.
This makes the LVH+LOG a tonnage-efficient way of deploying supplies (62 tons per 1,000 versus 100 tons for infantry logistics), but still only 80% as cost-efficient as infantry logistics (2.48 BP per 1,000 versus 2.0 BP for 10x infantry logistics units), so that there is an interesting and useful tradeoff between the two unit types. With this change I usually have a practice of using INF logistics for organic supply of frontline or other combat formations (e.g., artillery) and LVH logistics in rear-echelon HQs for resupply. Both have their advantages and disadvantages which IMO is how it should be - and was prior to 1.12 albeit in a rather contrived way.