Jungle is Always a go to , if i was starting my army again i would probably be in the same situation, go with a comon thing or try to think outside the box, where would the lizards be able to thrive and survive outside of a jungle? Maybe a swamp or a marshland... or even a lost oasis in the middle of a desert where the skinks have adapted their skin to camouflage with their surroundings outside of the oasis to keep enemies at bay
I know its a rough one but its a personal thing , try and create a background and make the colors and bases adapt to your army story.