I worry about a early investment into a pre dreadnought, it certainly provides some advantages in a strategic sense it is something our enemies cant ignore but it is also in a manner a strategic handicap to us a pre dreadnought would be a massive investment of resources that we would have to carefully protect in order to get the best use out of. On a tactical level a pre dreadnought could likely devastate any enemy formations and even most shore positions however a enemy pre dreadnought would pose a similar threat to our forces and our own pre dreadnought. I feel a better use of material would be a larger fleet of lighter vessels to use as merchant raiders even if the enemy has a powerful surface combatant of its own a pre dreadnought or perhaps a few heavier armored cruisers they're strategic and tactical threat to us would be minimized by our ability to outmaneuver them. However if we are fixed on the idea of a pre dreadnought I would suggest we utilize our second design to create a lighter cruiser or early destroyer obviously lacking torpedoes the potential damage these lighter screens could cause would be minimal but the greater number of these vessels would allow the pre dreadnought to cast a wider net as they scour the seas looking for targets of opportunity and alerting our pre dreadnought to any potential threat so it can move to deal with it or flee from it.
I feel like your examination of the capabilities of a predreadnought or any battleship is somewhat...unfavorable. Merchant raiding is no substitute for an actual navy when you need to do damage, and predreadnoughts are the main hitting power of modern (in game terms) navies. Not that they're called "pre-dreadnoughts", yet, they're just battleships.
They're not fragile little targets that go "pop" when they're hit and the enemies' ships will be at best
equal to ours, not superior. A battle line of battleships (predreadnoughts or not) will absolutely have the hitting power to brute force its way to the enemy's equivalent battle line. Torpedoes are a threat....somewhat....to a battleship, but they have incredibly limited range and speed compared to later eras and so they're much less of a threat.
Also you seem to have argued that because predreadnoughts are super dangerous and enemy ships could be similarly dangerous we should...not build the very dangerous ships because then we'd have to fight the enemy?
Obviously we need a fleet screen, but we also need a heavy hitter capable of taking on the enemies. We might not get a full modern predreadnought battleship, but we should be able to get a second-rate (literally second rate, as in "a battleship not meant to fight first-rate units on equal terms") battleship with a good balance of characteristics. The enemy will not be able to do better due to tonnage limits.
So my suggestion is: 4 techs, then either one revision and one more tech or four revisions depending on whether the first few designs need the extra 3 from not doing the technology to bring them up to spec. The two ships ought to be a light protected cruiser capable of filling the fleet screen and commerce raiding roles as necessary, and a battleship of about 10k tons. Probably with four ten-inch guns but we might be able to do four 11in or four 12in, if we make advances in steel and apply them to a large gun to keep the weight down. We could more or less take the Royal Sovereign class, remove the torpedo tubes, shrink the guns from 13.5in to 12in or so, and improve our armor steel so the main belt is 10-12in instead of 14-18in (with similar reductions in all other measurements), and reduce the range. That should give us the ~4k tons saved we'd need. Royal Sovereign used compound armor, by the way, so since we're using basic Krupp steel armor, from the sound of things, we're already ahead, and if we push further ahead, well, so much the better.