I can imagine that if Rams were squares,[...]
(Also, @Iden.) That was a rough classification system. I could see the "1x1" ladders in 'pre-deployed' form as 1x2 (or longer?) when carried by a couple of invading guys, especially as I was thinking that they'd potentially be bridging devices, as well as climbing (when advanced pathing indicates that the capability to crossing a 1-tile trench, if not wider, shortens the entry/egress to an area (or even allows pathing at all), and a tactical group has a ladder at hand that would fulfill the duty... this sort of thing would already need to be integrated with regard to finding paths related to wall-scaling. Ditto rams. Hand rams (the "SWAT Team's Knock" style, though for the life of me I couldn't, and can't think of the actual knicknames I've heard these things called) as "-" or "|" (or the doubled-line version, but I'm not sure that extended ASCII would survive both forum and browser rendering in all cases), 1x2/3 for the a large version, and 3x3 representing a roofed/armoured version. Really, that's all detail, though.
(And, besides, some castle defences (if not most?) deliberately
did employ 'awkward corner' physics to limit various attacks. Even the traditional 'handedness' of a spiral staircase was made to favour the defending (usually upper) swordsman against the attacking (lower) one, the latter's sword arm and reach impeded by the central pillar that had little negative (and even some positive) effect on the former's ability to be nasty with his pointy, sharp, heavy or otherwise inconvenient-to-the-enemy weapon.)
Maybe think of them as Classes A, B, C, D (handheld, two-man/dwarf/being, Standard?, Maxi) and while I
did only put in explosive items as a reference, they could be a menmonically handy Class E. Although knowing you lot, you'd be going for SuperBallistas the size of standard fortresses, and Super-Catapults that, while disguised as particularly large and well-designed oil derricks, were actually there to throw half a mountain onto the nearest (or next-nearest) Dark Fortress on the WorldGen map. In a single shot. So I won't get too hung up on
that system of classification, either, lest I have to shuffle the mythical (or not?) explosives class all the way up to Class X to make room.