I'd surprised if 12" and 15" were offered as a set-up - doesn't show up on the catalogues scanned in this forum.One thing you might try for the 15" which I attempted with some success, is to put a Camco tom mount on the base of a Camco tripod stand. Not as wide-based, I suspect, as the double tom holders (never seen one - perhaps Dolfan can elucidate) but, properly angled, probably enough to keep the drum sturdily in place unless you're playing thrash metal. Something I set up for fun one day, using such a system below but with a Pearl single brace instead. Never played it but sure looked impressive. A Camco stand works just the same.