Well, I'm still dragging my feet on the EXP thing, mainly because I strongly suspect it will end up not working right and bugging the **** out of the game, but I have been tinkering around with glitch building on the ships. That opens up a whole new level of design and is just cool as hell. By using glitches you can double up stuff in one spot, giving you extra room and also creating connection points that wouldn't otherwise be there. I just completed a build where I was able to double up six full size C Class engines into three spots, with it being just a single level taller, so the structural pieces work perfectly with them. Was also able to double cargo storage into landing gear and structural pieces, and also use structural pieces to hide my shield, shield jammer, reactor, fuel tank, grav drive and several weapons (I couldn't hide them all because I just ran out of room, but all the remaining external ones are on the bottom). The result is a ship that is compact and sleek, with nothing showing on the top but a docker, but is max shielded, fully armed and has a shit ton of cargo capacity. I did have to sacrifice a couple of habs, so there is no extra berthing space now and I guess my two human crew members are sleeping on the floor in the science lab or workshop, but **** 'em.
Also, you really can't stack stuff into hab modules, because the extra stuff shows up when you're in the interior of the ship and is really wonky. But other than that, this stuff is awesome. It really makes the design aspect almost limitless.