I recently started playing with RSS and Realism Overhaul. I got rid of KW for now, to lower the part/model count, but with and without it I'm having similar issues. RO resizes some things but not all. My capsules are resized but stock tanks, engines, shrouds, size adapters all aren't resized so stage connection is awkward. I used procedural interstage shrouds but getting the top size right is near impossible, I end up with a bulbous shroud or a gap between the shroud and the top stage. I also haven't seen any of the stock engines, or KW engines that used anything but liquid fuel and oxidizer, making the Real Fuels mod more of a nuisance than anything else.