Here's my 410 with a Kirk Arca-compatible clamp simply bolted on top of the Manfrotto QR plate. It's a
little [/i]clunky, but not nearly so bad as you might imagine.
And, for scale, here it is with a Canon 1-series body mounted via RRS L-plate.
Nill
p.s. Total investment, as I recall, about US$125. I got the head used for $100, the clamp used for $25 or so.