You can leave that 20gal right side up for now. When he gets older you will have to buy a bigger tank, but not right away. I know you guy's have an abundance of Anole's down there, but they require heating and some say Uvb lightning that's alot of care over a Crested Gecko. Cresties are quite social I might add, anything WC in Florida will be aggressive and not promote handling to well. Just my .02 cents.