savs love hiding under stuff. check under literally everything. (especially warm places like behind appliances, but be careful not to smush them) they can squeeze literally anywhere. (even under doors if small enough.) in my experience, they love dark closets, and somehow getting under the cabinets of computer desks.
keep the house as silent as possible and you will hear the little bugger scratching around. leave out some smelly ice in the middle of a room and he may go to it.
(it looks like you're due for a tank renovation soon. mesh is not good for savs, it kills the humidity. please check out varanustalk.com and savannamonitor.net, they are great resources.)