Maybe I don't understand correctly, or it's because I just own a K200D, but I have done similar things without investing such amounts of money.
If you use an older Metz 40MZ-2 (or -1 or -3) with an adapter SCA3701M2 or any SCA3702, and set camera and SCA adapter to rear curtain, the problem is already solved. As this flash/SCA combination doesn't understand about pTTL, there will be no pre flash. Camera can be in any mode (manual to be preferred), flash in any mode except TTL. The MZ40 has the same power as the newer "58" ones (calculation of GN has changed), and you can get it on eBay together with the SCA adapter for €50-80. With simple photo triggers, you can fire as many additional cheap old flashes as you want, and they all would automatically work with trailing curtain, too.
If you don't want the flash on top of the camera, you could use a Metz G16 power grip with the SCA3000A cable connector - unfortunately, these are not in production any more and offered seldom. But I just got a G16 (like new) from a German seller, and the SCA3000A brand new from South Africa, together including shipping for less than €35.
Last edited by RKKS08; 04-27-2012 at 06:03 AM.