I need help with a savannah monitor

[Sasami]

First I want to say I didn't let him get this bad, I found him like this and I want to try to get him back to health. He was at a pet store that didn't know how to take care of him; he was brought back after he supposedly bit the previous owner’s kid.
Anyway this guy had no heat at all save for room temp when I found him, and just a waterbowl in his small tank.



larger picture can be found here

I know he’s really thin and really dehydrated but I want to try to bring him back, then find him a good experienced home for him.
But I need to get him better first, if anyone has any advice that can help me that would be great. This isn't my first lizard and I’m not afraid of bugs, or getting bitten, so don't be afraid to tell me what to do, you may have to explain it but don’t' be afraid to tell me.

And I only had him in the tub once to see if he would drink some, and he did a little bit, also to try and get some of the dust, dead skin, and the random things that were stuck to him off by soaking

I don't have the heat or humidity specks at the moment but I will soon. Right now he's in a 75 gallon tank, with shredded coconut bark as bedding, he has a large sandstone basking rock set over a 25 watt heat pad (the rock is a good 5-6inches thick) a 150 watt inferred heat lamp a 60 watt heat lamp, 2 hides, 1 large water dish, and a screen lid with half of it covered with Plexiglas to keep in humidity (Should I cover some of the other side too?).

I've been feeding him reptile-aid and some stress ease, but I’m going to Pedialyte the next time I feed him I think.

I call him Zeus