transport ships (Already suggested by others) Designing Transports

[TingusPingus]

I do not need to go into much detail but one fact to note is there is wiki pages and info sites for the armed transports of WW2 and even WW1 if you look harder enough. Here is some examples of armed transports or also Merchant Cruisers.
RMS Alcantara (1913) BRITAIN
An ocean liner that was turned into an armed merchant cruiser from 1915-16
Armament: 8 × 6-inch guns and 2 × 6-pounder guns
RMS Empress of France (1913) BRITAIN
Same treatment but this one had initially 8 x 4.7 inch guns but eventually got the same as the Alcantara
Here is a link for the American attack transports: https://en.wikipedia.org/wiki/Attack_transport
This is a link for WW2 of course, but this shows there was uses for it.
Problems I noticed is I can barely find much info on similar ships for the other powers during WW1, some even in WW2, and I can see why it would be not desired unless you had to use info from other similar tonnage ships that had guns to make it a reason to add, however the concept can bring a little something more interesting to campaign
Combat is fine and dandy but so is keeping a steady flow of income, what you can do is have maybe a difficulty system that makes you start with less income than usual, where you are expected to have to start out using the transports for your builds and needing to slap together essentially a cruiser sized yet destroyer armor weak vessel to count as your main fleet until you can get enough research done to make money to out-date them. But even if your armed transports do eventually get fazed out, their weapons can still do some damage and support the actual fleet, but as usual they are by default controlled by AI and can be given command to you if you need the numbers.
It is a bit of a stretch, but something I believe many would like to see, it can also open more to bringing in smaller caliber guns nearly close to auto-cannons that was used against PT boats and lighter vessels.