I would have thought that any of the devices shown so far can be fitted sideways (or upside-down for that matter), if I understand you right (I am a bit puzzled by your "not enough room" point - if there's enough room to apply a screwdriver to your present device then anything with a permanent shank instead should fit also, but I may be missing something).
My only other suggestion would be to fit something elsewhere in the supply pipe where perhaps there is more room, but I realise this may not be viable..
You are right about the 2-fat-ladies one being the "screwy thing". Incidentally this device doesn't "tighten" so much as just turn through 90 degrees, if you continue to turn it it will then open again after another 90 degrees, then close again after a further 90 degrees and so on - whichever direction you turn it.