AFAIK, Chameleon skink stalker is not Seraphon unit, but Liazardmen, so can be only taken as ally and won't benifit from allegience. Shadowstrike itself specifies that you need Chameleon Skinks unit, not just Chameleon Skinks keyword. So your build is invalid.
Strongest shadowstrike list is 2x40 skinks and 6 ripperdactyl riders. Terradons, unfortunately, benefit less from the battalion bonus, than ripperdactyls. 10 chama skinks is viable too. So, considering your units, I'd go for 3 ripperdactyls and 5 chamas and add any number of skinks you have in the second unit.