The problem with all of these ideas is that they simply carry forward the long-standing conflation of ship
size with ship
role that has been in SE from the beginning.
Honestly, the actual components are what make it what it is. The size is simply a function of the size it needs to be and your ability to build ships of that size. Battleships of the 1st World War were 18-24000 tons. Battleships of the Second World War were 30,000 and up. Were the old battleships reclassified as cruisers because of this?
So while I agree that the current tech tree of ship hulls is too rigid in SE I don't think the solution is the right one. I'd stop calling the hulls by any 'class' names at all and use the
design names to differentiate the ships. Then ship construction can just let you build bigger ships and you design them as needed for their role. Proper economics of scale in the design system would result in the familiar 'capital ships' and 'escort' classes without any artificial categories needed.