Leo advice.....
Leo's come from very arid rocky desert habitats and thus are accustomed to very low humidity levels, high ones acheived by spraying, as said, will indeed lead to respitory infections in the long term, along with encouraging bacterial growth build up.
A small hide containing damp moss or a damp flannel half on/half off the heat mat will help them during shed time, otherwise a dish of water is all the moisture they need.
A heat mat covering 1/2 to a 3rd of the floor space, plugged into a thermostat (either mat or pulse) will see to all their heat needs, you are looking to acheive a hot end temp of around 32/33c with a natural gradient acheived down to their cool end at room temps (most standard 11x11 and 11x17 mats have no probs acheiving this).
As said it is this belly heat that is a must, as without it Leo's cannot digest their food properly, in the wild they would hide away during most of the day and venture out in the evening to lay belly flat down onto the sun heated rocks, they then lay and absorb this heat up through their belly. No additional lighting is needed at all. you could have a blue/red nightime viewing light for your convenience as you like, these are cool lights, therefore don't effect the ambient temps, I just have a lamp in my rep room which is blue, so no lighting at all in individual vivs.
Nav is a good lad and very devoted keeper and his advice here is all about helping you the OP, certainly not about posturing, belittleing or ear bashing, as some do I agree, in the end we all want is best for the animals in question :2thumb:. Take a look on my home page, there I have a list of really good leo sites with loads of caresheets and info to help.