could try skeet. i think it was skeet who got mine. well he can get everything else. an s rail and sp dovetail fits so so nice on an ion but uniomounts are good enough.
Eclipse also do an on/off with a purge but I can't seem to see it on the site. You could also get yourself a unimount but I really dont like them, awkward to fit and akward to use. I say go with Eclipse or CP.