Nile Monitor rescue...have some questions.

[buffcoat]

Today my better half surprised me with another reptile. She, as well as some of yall know, I'm not a huge fan of reptiles with legs. I would like to "start small" though. Anyway, after seeing this guy and his conditions I knew we (I) were going to keep him on the condition that she finds a new home for him asap. I just do not have room for a monitor at this time. He was given to her in a 10 gallon tank with a screen top, that astroturf stuff for tanks, a small water dish and some crickets.

What I have is a 55 gallon tank. I was going to cut a piece of wood to fit the top, mount some lights uvb/uva, maybe a heat omitter, big water bowl some hides. Now is this sufficient until we find him/her a home? I've read that they need 80-90 ambient day, drop to 70-80 night and a basking of 120ish?

I know some might ask why Im keeping this not being prepared but if you would see this lil guys setup you hopefully would agree with me.

Also what's the best substrate to use?

Humidity levels? There are so many conflicting sheets.

Thanks guys an gals. And one more thing, our animal shelter does not take reptiles. So what would be the next best thing to finding this guy a home?